In zoology|lang=en terms the difference between trematopid and trematoid
is that trematopid is (zoology) any member of the trematopidae while trematoid is (zoology) of or relating to the trematoda.
As a noun trematopid
is (zoology) any member of the trematopidae.
As an adjective trematoid is
(zoology) of or relating to the trematoda.