sporangium vs spore case

sporangium and spore case both are nouns.

Word	Noun	Adjective	Verb	Adverb
sporangium	Yes	No	No	No
spore case	Yes	No	No	No

As nouns, sporangium and spore case are synonyms defined as:

Other synonyms of sporangium include spore sac.

sporangium (noun)	spore case (noun)
organ containing or producing spores	organ containing or producing spores
	specialized leaf branch in certain aquatic ferns that encloses the sori or clusters of sporangia