sporangium vs spore sac

sporangium and spore sac both are nouns.

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

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

Other synonyms of sporangium include spore case.

sporangium (noun)	spore sac (noun)
organ containing or producing spores	organ containing or producing spores