Pythiaceae vs fungus family

Pythiaceae and fungus family both are nouns.

Word	Noun	Adjective	Verb	Adverb
Pythiaceae	Yes	No	No	No
fungus family	Yes	No	No	No

As nouns, fungus family is a hypernym of Pythiaceae; that is, fungus family is a word with a broader meaning than Pythiaceae:

Pythiaceae: fungi having sporangia usually borne successively and singly at the tips of branching sporangiophores
fungus family: includes lichen families

Pythiaceae (noun)	fungus family (noun)
fungi having sporangia usually borne successively and singly at the tips of branching sporangiophores	includes lichen families