beard vs imperial beard

beard and imperial beard both are nouns.

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

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

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

beard (noun)	imperial beard (noun)
tuft of strong filaments by which e.g. a mussel makes itself fast to a fixed surface	a small tufted beard worn by Emperor Napoleon III
hairy growth on or near the face of certain mammals
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)	imperial beard (verb)
go along the rim, like a beard around the chin