green manure vs manure

green manure and manure both are nouns.

Word	Noun	Adjective	Verb	Adverb
green manure	Yes	No	No	No
manure	Yes	No	Yes	No

As nouns, manure is a hypernym of green manure; that is, manure is a word with a broader meaning than green manure:

green manure: a growing crop that is plowed under to enrich soil
manure: any animal or plant material used to fertilize land especially animal excreta usually with litter material

green manure (noun)	manure (noun)
a growing crop that is plowed under to enrich soil	any animal or plant material used to fertilize land especially animal excreta usually with litter material

green manure (verb)	manure (verb)
	spread manure, as for fertilization