This is a lot bigger of a conversation than i thought lol
Differences between 200-400-600-800?
When I watch Naroditsky's speedrun 1000 rated players look similar to 2000 rated players. They both get blown of the board and they look like toddlers who have just learned how the pieces move.

I was a 600 3 years ago. I'm 2100 now.
There's a few things that stand out as being most impactful in my journey from say, 600 to 1000.
1) Opening principles - having a general sense of direction with the purpose of the opening moves vs literally playing random moves with no real purpose.
2) Solving basic checkmates and tactics. This also helps with pattern recognition and board vision - which is a real problem sub 600.
3) This was immediately obvious during my rise from say 1000 to 1200, but watching the likes of John Bartholomew's climbing the rating ladder really helped me with regards to planning. Listening to his thought process and how it changes based on what he see's, etc - I saw a near immediate 100 point rating gain in the 3 days following a binge watch of that series.
But in a nutshell, it can be summarised as a lack of board vision and sense of direction - which is trained through tactics and learning plans, strategy, ideas etc.
Daniel Naroditsky's speedrun videos are 5000x better than John Bartholomew's, I highly recommend every beginner go check out those speedrun videos

Hi guys. I wanted to jump In and post in this thread because I believe I have some valuable insight into Elo. I am currently around 800 rating, and began my climb from 300 a month ago. I want to point a few things out as I’ve played other games with elo ranking systems and have achieved high master and even grandmaster in sc2. In terms of what separates ratings, it’s important to note, access to effective engines and game reviews destroys all notions of what an 800 is to anybody who broke that rating more than maybe 8 years ago. For instance, my buddy who is just starting his grind, is losing consistently to 250-300 players and can mop the floor with the AI player rated 1000. The baseline of player increases as access to developmental tools increases. The average player is significantly better than pre readily available analysis. My climb so far, the biggest things I’ve noticed, are less hanging pieces, and less direct tactics. Generally, the lower I was, the more readable the attacks were. Never a discovered check or skewer, just basic things that can be deflected like scholars mate attempts

Having read through all the posts for this topic, thought I would throw my hat into the ring as very few comments from players who are at these levels 200 - 400 - 600 - 800 that the original poster is asking about.
My Rapid is around 470 at the moment while my daily is almost double that. I am playing mainly 30min games and still feel the time restraint, presume most of my blunders come from that pressure and conclude I am a slow thinker but enjoy the game in a one sitting approach.
I am a few weeks in from a 50 year gap, and only knew how the pieces moved and a few ways to finish off the games, so dropped below 300 rapid with my first few games, and decided to start at the beginning and have some kind of an opening to get me through and survive so I can make the games last longer, as well as some puzzle practice to make me more aware of possibilities.
Around 300 - 400 I have found it is about survival, pieces get thrown at you in poorly thought out one or two piece attacks that are fairly easy to read and defend, the opponent quickly blunders or just quits after this, so am learning that counter attacking is a powerful way to play through this level.
Playing against higher ratings, 600+ Rapid, I find that the openings are more calm and much more about getting the troops into position before the big fight to control the centre of the board, though still get some jabs at my defences with I piece probes and attacks that seem a little shallow or a fail to understand the reason for them. I loose most of these games by being outplayed during the middle phase, lacking tactics and not understanding what my opponent is up to until it is too late, though sometimes manage to defend and then counter attack when there are fewer pieces on the board and things seem a little simpler.
I have not played anyone over 700 rapid yet so can not comment on that level, but would get blown away in the middle game presuming it lasts that long I expect.
My observations are that everyone blunders, but that is not always the reason games are won or lost. There is a massive gap in knowledge between each of these levels that higher ranked players seem to have forgotten. Quality information is hard to come by that deals with these gaps without getting so technical that it goes right over your head. A simple to learn opening strategy that can cope with anything that gets thrown at it, and some tactical knowledge to have at least a bit of an idea of how to approach the mid game seem hard to come by. This is where I think most help is needed from players like myself. A lot of our mistakes are dismissed as blunders but they are lack of knowledge, we dont even know what we dont know at this level.

A lot of our mistakes are dismissed as blunders but they are lack of knowledge, we dont even know what we dont know at this level.
I agree!!
I'm 817 after like 7 months and had a huge blockage in getting out of 600s, got through 700s really quick. I rarely lose because I was beaten in a positional game. I rarely even lose because of tactics. I mainly lose from blundering and time. When I moved my time control up I went on a 7 game winning streak. I think this is is most 800s.
200-400 - they just dont understand the dynamics of the game, moves are random. They move cause they have to. No plans. Serial Blundering
500-650 - they know an opening variation, they cant do middlegames so your rarely get close endgames. Mate on the board in middlegame mostly because they cant spot when theyre being mated. 2 big blunders per game, and very prone to blunder spiraling
650- pretty much 800 and something - they can beat any newbie. They know an opening to a not so bad degree. More patience and middlegame understanding, rerouting, space, kings safety, piece activity. 2 Blunders a game max, , with not so much blunder spiraling. The biggest change is that after 700 or so, one learns that losing a pawn (unless its a gambit) is also a very serious blunder. At this level your start playing a few endgames, so pawn structures and keeping pawns becomes visible for the first time. Tactically a bit better. At this level I win by getting into my opponents position. Which takes time. At this level your start to play actual endgames besides 2 queens or 2 rooks because the game got close till the end.
What is the difference between a player that starts at 200 rating and a player that starts at 400 rating?
I would say 90 percent of the time a person only rated 200 is someone that created a new account and is purposely losing so he can troll on the forums.
The other percent of the time is just lack of chess aptitude, which some people have. The goal for these people would be to be increase their board vision by playing lots of games with the longer time controls, which sadly, most people don’t do.
I know people that are rated about 800 on blitz at chess.com and I’m surprised when I hear they are rated that low people these same people often play very solidly with me otb.
Differences between 400-800 stem from having or not having practical experience. The fact that they are still that low is because they often make silly mistakes. I play with two different 800 rated players and one of them often makes silly mistakes or just drops pieces for no compensation. The other invested a lot of time learning various openings but when taken out of book he doesn’t know what to do.
Sadly these two will never improve because they don’t review their losses.
Actually one of the two is improving because he plays longer time controls at another club he goes to and goes against strong players.
I noticed when I play him with these time controls he just blitz’s out his moves and I end up destroying him.
I for example am learning how to play at longer time controls. I’m starting with 30 minute games. I noticed I destroy people who match my speed but when faced with people who think, I tend to lose. So I have to train myself to think of candidate moves on their time, and spend more time on my moves when they are thinking more about their moves.
So I can say with certainty that time management is a big part of the game and beginners especially need to think a long time about their moves with a checklist of things to go over when thinking about their moves.
I learned chess slowly because I wasn’t given a check list nor did I read any books. I learned strategy by just playing stronger opponents. If I were to give advice to my younger self I would say spend time analyzing your losses and go over master games, and play games with longer time controls.

The assumption you will improve from reviewing your losses is BS. Because I review my losses. Stockfish is a terrible teacher. it will suggest moves that make no sense. And annoyingly i have to import games to lichess.
Been stuck at 600 for a year.
Maybe you can try to focus on the moves that do make sense to you. I also find that I may not understand the complex lines the engine suggests.
Most people (myself included) above a certain rating threshold (for example, 1800) believe that the ratings of beginners are extremely unstable and that 400 is approximately the same skill level as 600.
I've seen a lot of posts about the differences in ratings below 1000, and generally, higher-level players summarize it as "blundering less and less", but after reading several beginner comments, it seems to me that there is more to it than that!
This is an interesting topic. I observed the same: Higher rated players group 400s and 800s together while the low rated players themselves experience huge differences between 400 and 600. Part of it probably has to do with rating distance. If you are an 1800 rated player, you will crush a 700 rated player just as easily as a 400 rated player. I have the same feeling the other way around, players rated 2000 or rated 2400 are the same to me. They are indistinguishable to me.
The second factor that comes to mind is that there is some truth to the idea that a 400 is approximately the same skill level as a 600. Both players play a blunder or a mistake every other move, which leads to a much higher variance. And most of the players at that level haven’t even played enough games for a reliable sample size. My guess is, due to a higher number of games played, that a 1600 rated player will beat a 1300 rated player much more consistently and reliably than a 700 rated player will beat a 400 rated player.
I see huge difference between 800s and 400s. Especially if we are talking about blitz ratings. 800s can play 30 move games without 1 move blunders, 600s can't do that. Watch two 600 rated players play 10 thirty move games and they will make a 1 move blunder in each and every single one of them. On the plus side, 600s will look like they are trying. If I look at 400 or sub 400 elo chess games I genuinly can't tell if they are playing bad on purpose or not. Their games look fake. When I watch 600s at least it is obvious that they are not faking games. I think ratings around 500-600 are pretty stable if the player has played at least 100 games of chess. My own rating have always been oscilating about 150 points and I am now rated 1900 rapid, 1800 blitz.
Also, I am 1800 blitz and I can give a full queen to a 400 and win every single game, they will never beat me, on the other hand, if I give a full queen to 800-900 blitz players I have a decent chance of losing that game.