beard vs stubble

beard and stubble both are nouns.

Word	Noun	Adjective	Verb	Adverb
beard	Yes	No	Yes	No
stubble	Yes	No	No	No

As nouns, stubble is a hyponym of beard; that is, stubble is a word with a more specific, narrower meaning than beard:

beard: the hair growing on the lower part of a man's face
stubble: short stiff hairs growing on a man's face when he has not shaved for a few days

Other hyponyms of beard include fuzz, imperial, imperial beard, beaver, goatee, vandyke, vandyke beard, Attilio, soul patch.

beard (noun)	stubble (noun)
tuft of strong filaments by which e.g. a mussel makes itself fast to a fixed surface	short stiff hairs growing on a man's face when he has not shaved for a few days
hairy growth on or near the face of certain mammals	material consisting of seed coverings and small pieces of stem or leaves that have been separated from the seeds
the hair growing on the lower part of a man's face
a person who diverts suspicion from someone (especially a woman who accompanies a male homosexual in order to conceal his homosexuality)
a tuft or growth of hairs or bristles on certain plants such as iris or grasses

beard (verb)	stubble (verb)
go along the rim, like a beard around the chin