hubby vs house husband

hubby and house husband both are nouns.

Word	Noun	Adjective	Verb	Adverb
hubby	Yes	No	No	No
house husband	Yes	No	No	No

As nouns, house husband is a hyponym of hubby; that is, house husband is a word with a more specific, narrower meaning than hubby:

hubby: a married man; a woman's partner in marriage
house husband: a husband who keeps house while his wife earns the family income

Other hyponyms of hubby include benedick, benedict, cuckold, family man, househusband, uxoricide.

hubby (noun)	house husband (noun)
a married man; a woman's partner in marriage	a husband who keeps house while his wife earns the family income