testa vs seed coat

testa and seed coat both are nouns.

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

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

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

Other synonyms of testa include episperm.

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