As nouns the difference between seal and phoca
is that
seal is a pinniped (pinnipedia), particularly an earless seal (true seal) or eared seal or
seal can be a stamp used to impress a design on a soft substance such as wax while
phoca is a seal.
As a verb seal
is to hunt seals or
seal can be to place a seal on (a document) or
seal can be (dialectal) to tie up animals (especially cattle) in their stalls.