greybeard vs patriarch

greybeard and patriarch both are nouns.

Word	Noun	Adjective	Verb	Adverb
greybeard	Yes	No	No	No
patriarch	Yes	No	No	No

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

Other hyponyms of greybeard include codger, old codger, antique, gaffer, old-timer, old geezer, oldtimer.

greybeard (noun)	patriarch (noun)
a stoneware drinking jug with a long neck; decorated with a caricature of Cardinal Bellarmine (17th century)	the male head of family or tribe
a man who is very old	any of the early biblical characters regarded as fathers of the human race
	title for the heads of the Eastern Orthodox Churches (in Istanbul and Alexandria and Moscow and Jerusalem)
	a man who is older and higher in rank than yourself