housepaint vs house paint

housepaint and house paint both are nouns.

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

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

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

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