These chess variants have different initial positions than chess.
Otherwise the rules are the same, the table is the same, and the pieces are the same (but not necessarily in the same number).
Different piece order
Chess 960
Random initial position on the back rank
Mongredien Chess
Same minor pieces on the same side
Transposed pieces
Bishops and knights are swapped
Fianchetto Chess
Rooks and bishops are swapped
Reversed Royals
Black queen and king are swapped
Other symmetric
Advanced Pawn Chess
Pawns start on the third rank
Corner Rook Chess
All pieces except rooks start one step advanced
Sixteen Pawns
Twice as many pawns
Pawn Endgame
Only pawns and kings
Upside-down Chess
Reversed initial position, the pawns start one step away from promotion
Asymmetric, balanced
In these variants though the initial position is not symmetric, the chances may be more or less equal.
The exact number of pieces is adjustable.
Pawns for Queen
White has no queen, but has much more pawns instead
Pawns vs Knights
White has only pawns, and Black has knights and a single pawn
Knight Army
Black has seven knights and more pawns
Queens vs Knights
Black has only queens, and White has only knights
Unequal
These variants explicitly prefer one player (white) to equalize players with different skills.