forefather vs patriarch

forefather and patriarch both are nouns.

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

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

forefather: the founder of a family
patriarch: any of the early biblical characters regarded as fathers of the human race

forefather (noun)	patriarch (noun)
the founder of a family	the male head of family or tribe
person from an earlier time who contributed to the tradition shared by some group	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