If list has length s, Differences[list, n] has length s-n. »
Differences[m, {1, 0}] or Differences[m, 1] finds the successive differences of rows in a 2D array or matrix m. Differences[m, {0, 1}] finds the differences of columns.
Differences[list, {n1, n2}] is equivalent to Differences[Differences[list, n1], {0, n2}].