seed coat vs episperm

seed coat and episperm both are nouns.

Word	Noun	Adjective	Verb	Adverb
seed coat	Yes	No	No	No
episperm	Yes	No	No	No

As nouns, seed coat and episperm are synonyms defined as:

seed coat and episperm: protective outer layer of seeds of flowering plants

Other synonyms of seed coat include testa.

seed coat (noun)	episperm (noun)
protective outer layer of seeds of flowering plants	protective outer layer of seeds of flowering plants