Methuselah vs greybeard

Methuselah and greybeard both are nouns.

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

As nouns, Methuselah and greybeard are synonyms defined as:

Other synonyms of Methuselah include graybeard, old man.

Methuselah (noun)	greybeard (noun)
(Old Testament) a patriarch (grandfather of Noah) who is said to have lived 969 years	a stoneware drinking jug with a long neck; decorated with a caricature of Cardinal Bellarmine (17th century)
a man who is very old	a man who is very old