seed coat vs testa

seed coat and testa both are nouns.

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

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

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

Other synonyms of seed coat include episperm.

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