As nouns the difference between docker and cocker
is that
docker is one who performs docking, as of tails or
docker can be a dockworker while
cocker is (dated) one who breeds gamecocks or arranges cockfights or
cocker can be a rustic high shoe, half-boots or
cocker can be (uk|informal) friend, mate.
As a verb cocker is
to make a nestle-cock of; to indulge or pamper (particularly of children).