leptosporangium vs spore case

leptosporangium and spore case both are nouns.

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

As nouns, spore case is a hypernym of leptosporangium; that is, spore case is a word with a broader meaning than leptosporangium:

leptosporangium: a sporangium formed from a single epidermal cell; characteristic of the Filicales or of almost all modern ferns
spore case: organ containing or producing spores

Other hypernyms of leptosporangium include sporangium, spore sac.

leptosporangium (noun)	spore case (noun)
a sporangium formed from a single epidermal cell; characteristic of the Filicales or of almost all modern ferns	organ containing or producing spores
	specialized leaf branch in certain aquatic ferns that encloses the sori or clusters of sporangia