I think a double attack is when a piece has two threats (pawn+Piece, Piece+check etc...)
Fork is when one piece threatens two pieces (Knight, bishop, rook, queen, king)
So, it is a double attack if multiple pieces are involved but a fork when a single piece is attacking two pieces?
No, it's a double attack if a piece is attacking multiple things at the same time
A fork is only if a piece is attacking multiple pieces at the same time
Look at my example #2, white plays Qb3 attacking the b7 pawn, and at the same time putting pressure on the f7 square.
In example #1 it's a fork as the knight is attacking two pieces at once
Ok, the more complex question then is: what is the difference between "Fork" and "Skewer"? Why is it used in the "this or that term" tactic even if the (misleading) image is the same? This is really difficult and I've never explained it to myself, I've found many examples of "Fork" with rook, bishop that are equal to "Skewer"....but no one explains to me why he uses one term rather than another
Agreed with above post. Fork is one piece attacking two. Double attack is two pieces attacking one.
No, not necessarily 2 attacking 1. Could be 2 attacking 2 different pieces (usually one from discovery). Se the previous post of mine.
The most common use is "there is a double attack on X," "There is a triple attack on X/"
And those attacks do not have to come from a single move.