The ordp command computes the p-adic order of the p-adic number a (evalp(a, p) in the 2-argument case), which is the degree of the leading term.

The valuep command computes the p-adic valuation of the p-adic number a (evalp(a, p) in the 2-argument case), which is 1/p^ordp(a).

For an explanation of the representation of p-adic numbers in Maple, see padic[evalp].