What makes an opening system different than a standard opening?

What makes openings like the Stonewall, Colle, London, different than the English, Italian, and Caro-Kann?

@1

"What makes openings like the Stonewall, Colle, London, different than the English, Italian, and Caro-Kann?"
++ Not much. In system openings you have several transpositions and you can play it more or less against most opposition.
Stonewall: ...f5, ...Nf6, ...e6, ...d5, ...c6, ...Nbd7, ...Bd6, ...O-O, ...Ne4, ...Ndf6
Colle: d4, e3, Nf3, c3, Bd3, O-O, Re1, Nbd2, e4
London: d4, Bf4, Nf3, e3, c3, Bd3, O-O
You can also play the English, or Italian as a system.
English: c4, Nf3, g3, Bg2, O-O, Nc3, d3
Italian: e4, Nf3, Bc4, d3, O-O, c3, Nbd2

"System Openings" - Which DO NOT WORK - are openings of misconception where noobs get the idea that they can play them no matter how the opposing players respond.

For example, many of these lowly nobodies thing the following can be played as White against anything (In parenthesis are cases where they are really bad):

London System (Modern Defense)

Kosten's old English advice from the 90s of playing 1.c4, 2.g3, 3.Bg2, and 4.Nc3 against everything (1...e5, 2...Nc6, 3...f5, 4...Nf6)

Stonewall Attack (Anything where Black has not committed to d5, amongst others)

King's Indian Attack (Anything where the Black LSB is not blocked behind the pawn chain - basically only effective vs the French and 2...e6 Sicilian)

Colle System (Anything where the LSB is not blocked behind the pawn chain, like if 3.Bf5 or 3.Bg4, White MUST play 4.c4 and deal with the Slav, and it's terrible against Fianchetto Defenses like the Kings Indian, Grunfeld, Modern, or Leningrad Dutch)

Chess is hard, and there is no cookie-cutter approach that works!

There are many more system openings.
King's Indian Attack is not only viable against the French 1 e4 e6 2 d3 and the e6 Sicilian 1 e4 c5 2 Nf3 e6 3 d3, but also against Caro-Kann 1 e4 c6 2 d3 and even against 1 e4 e5 2 Nf3 Nc6 3 g3.
Leningrad Dutch ...f5, ...Nf6, ...g6, ...Bg7, ...O-O, ...d6 is also possible against 1 d4, 1 c4, 1 Nf3 and reverse as white.
Botvinnik c4, g3, Bg2, Nc3, e4, Nge2, O-O
Hedgehog c5, b6, Bb7, g6, Bg7, a6, Nf6, O-O, Re8
Hippo g6 Bg7 b6 Bb7 d6 e6 Ne7 Nd7 O-O

The KIA sees White fighting for equality against the Caro-Kann (3...e5!) and is very weak against 1...e5 systems.  Anything where Black can play ...Bg4 or force White to play h3 sees White struggling in the Kings Indian Attack.

What's wrong with the london?

@7

"What's wrong with the london?"
++ Nothing at all London is fine and has seen play at top level: Carlsen, Kramnik...
Also the other system openings have seen play at high levels.

Why do I have to pay attention to my opponent's moves in "theory" openings?

@9

"Why do I have to pay attention to my opponent's moves in theory openings?"
++ Your opponent is not forced to play along the main line, he may deviate as he sees fit.

I indicated above - The London System fails to the Modern Defense.

I never said these openings cannot be played in the right circumstances.  The London is fine against 1...d5.  The Colle is fine if Black plays ...e6 WITHOUT moving the Bishop outside the pawn chain.

What I said is that using any of these as a "system", as in "Play it against everything no matter what Black does", will lead to utter failure.

The Torre is bad against 1...d5.

The Lonton is bad against 1...g6

The Colle is bad when the Bishop goes to g4 or f5 and White must instead transpose to the Slav with 4.c4.

You can mix and match these and you'd be fine.

The London is not so hot against the King's Indian or Dutch either.  It works best against non-fianchetto defenses.  So something like:

Torre vs KID/NID

Colle against 1...Nf6/2...d5, transpose to slav if 3...Bf5 or 3...Bg4

London against 1...d5

2.Bg5 against the Dutch

2.e4 against the Modern

You'd have a solid, legit repertoire with good winning chances, and outside of the Slow Slav, you'd never have to play c4.

But to just play the London as a system, here's what you'd have:

Winning chances against 1...d5 or Nimzo setups

Equality at best against King's Indian and Dutch setups

A worse position against the Modern Defense

How on earth would you be worse against the modern defense?

 You dont. ever.

Simp on.

Precisely the way that both London gurus, like Lakdawala, and Modern Defense experts, point out.  Dominating e5!

1.d4 g6 2.Bf4? Bg7 3.e3 d6 4.Nf3 and now Black has a choice, both of which lead to a slight advantage:

4...Nd7

4...Nc6

Personally, I prefer and know more about the latter, and have played the latter many times when I was playing the Modern Defense against 1.d4 around 2015 .

After 4...Nc6 5.h3 e5, White's best move is actually 6.Bg3 (NOT 6.Bh2?! =/+) and this is somewhere in between equal and slightly better for Black based on actual GM and IM analysis, not what number some computer gives.  Computers are terrible with assessing openings.

Even worse for White, and more common below 2200, is 6.dxe5? dxe5 7.Qxd8+ Kxd8 8.Bg5? f6 9.Bh4 -/+.

White is "virtually" a piece down.  It will take for ever, and major weakening of the White pawn structure, just to get the DSB into the game.  Black does not have that problem.  A simple ...Bf8 solves that problem.  Black can also play on either side of the board.  White has nothing on the Kingside, and no advantage at all on the queenside.

I am not making this up.  Study various books, like Lakdawala's books on the London and the Modern Defense, the books on Duncan Suttles's games (he is an expert on the Modern Defense), etc.  The London is no good against the Modern, and while they will say in London System books that it is PLAYABLE against the KID and Dutch, it is equal at best for White there.

What players that just try to mimic moves don't understand is that one of the keys to the London System is to control the central dark squares, particularly d4 and e5.  With Nf6 played, the a1-h8 diagonal is blocked for a Bishop on g7.  So it takes Black a lot longer to get in ...e5, with more pieces stuck trying to hold control of e5, like 1.d4 Nf6 2.Nf3 g6 3.Bf4 Bg7 4.e3 d6 5.h3 O-O 6.Be2 Nbd7 7.Nbd7 Qe8 8.O-O e5 9.Bh2 Qe7 and as you can see, it took Black a lot longer to get in e5 and more pieces to hold it.

With 1...d5,  lack cannot play ...d6 any more and that weakens e5 even more.  This is why the London is BEST against 1...d5.

But with neither ...d5 nor ...Nf6 played, ...e5 is way too easy for Black to achieve, and by move 5, White is already being pushed back.  The Bishop on g7 is directly impacting e5 with no Knight on f6 and the d-pawn is on d6 rather than d5, strengthening Black's grip on e5.

But if you still think the London is so great against the Modern and absolutely do not trust what GMs say, IMs, and then experts like myself that have played the opening before, go right ahead and fail.

I laid out for you what is virtually the ideal d4-without-c4 repertoire for you above.  Another that would say the same is Simon Williams, who has done videos for chessbase on the Torre, London, and Colle.

Thanks, I never knew. 

Also, I should clarify why I recommend the Colle after 1...Nf6 and 2...d5,  but the London against 1...d5.

If you are not a London player, leaving that out and just playing the Colle and Anti-Colle systems against 1...d5, which includes a transposition to the Slow Slav in the Anti-Colle, is perfectly fine.

But for those with London Experience, it can be a tick better than the Colle in 1...d5 systems.

So why not the London after 1...Nf6 and 2...d5?

The problem has to do with move order.  In the Colle and Torre, 2.Nf3 is played.  But in the London, 2.Bf4 is best against 1...d5 because of a very annoying line:

1.d4 Nf6 2.Nf3 d5 3.Bf4?! c5 4.e3 Nc6 5.c3 Qb6 6.Qb3 c4 7.Qc2 Bf5! with an excellent game for Black.

This is the ultimate reason why everyone plays 2.Bf4 and 3.e3 now, to avoid this very line.  The development of the Knight is slightly delayed to avoid all of this and develops the Knight once those shenanigans are avoided.

But you don't play 2.e3 in the Colle or 2.Bg5 in the Torre (the latter is actually the Trompowsky, which is a different opening than the Torre), so in both of those, White plays 2.Nf3, but if 2...d5, now 3.Bf4 leads to that same problem above, and hence why I say the Torre meshes better with the Colle than the London, but in cases where Black plays 1...d5, there is absolutely nothing wrong with playing the London instead of the Colle via 2.Bf4, especially if you already know the London.  It is just extra work for those that don't know it when they could just as easily play the Colle.

@4

Why do you think the King's Indian Attack is bad against Bf5?

Also, Botvinnik's English opening setup is good against 1.c4 e5

English setup is bad against 1...c6 and 2...d5 (Caro Kann Defensive), because you can't even reach the shape without the pawn on c4 being either taken or cxd5. 

I think I worded it poorly, when I said "English Setup" I was referring to the Botvinnik Setup. But what makes it bad against 1...c5?

I've seen the text say Caro-Kann Defensive when 1.c4 c6 is played. But I don't really know what that opening is.

Yes! Great question! I haven't seen much written on this subject, so I put in a several hours and tried to catalogue all the opening category "types" of opening names. I mean what makes something an "Opening" versus a "System" versus a "Formation" and so on. Well...there is an answer and I made a roughly 45 min YouTube video on it. The video is simply a list of the various opening types I could think of and I have at least one example of each.

Haven't seen anyone do something exactly like this before, so I was happy with this topic idea.

As a London player myself, I can attest to the fact that a system is basically a set of moves, (although the order could change depending on the opponent's moves) which you can play against many openings.