house paint vs housepaint

house paint and housepaint both are nouns.

Word	Noun	Adjective	Verb	Adverb
house paint	Yes	No	No	No
housepaint	Yes	No	No	No

As nouns, house paint and housepaint are synonyms defined as:

house paint and housepaint: paint used to cover the exterior woodwork of a house

house paint (noun)	housepaint (noun)
paint used to cover the exterior woodwork of a house	paint used to cover the exterior woodwork of a house