Order

Order[expr1, expr2] gives 1 if expr1 is before expr2 in canonical order, and -1 if expr1 is after expr2 in canonical order. It gives 0 if expr1 is identical to expr2.

Examples

Compare canonical ordering:

Order[a, b]
(* 1 *)

Identical expressions:

Order[x^2, x^2]
(* 0 *)

Reverse order:

Order[b, a]
(* -1 *)

Please visit the official Wolfram Language Reference for more details.