Differences
Differences[list] gives the successive differences between consecutive elements: {e2-e1, e3-e2, ...}.
Examples
Compute differences:
Differences[{1, 4, 9, 16, 25}]
(* {3, 5, 7, 9} *)
(* Second differences *)
Differences[{1, 4, 9, 16, 25}, 2]
(* {2, 2, 2} *)
(* Inverse of Accumulate *)
Differences[Accumulate[{1, 2, 3, 4, 5}]]
(* {2, 3, 4, 5} *)Please visit the official Wolfram Language Reference for more details.