house vs mansion

house and mansion both are nouns.

Word	Noun	Adjective	Verb	Adverb
house	Yes	No	Yes	No
mansion	Yes	No	No	No

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

As nouns, house and mansion are synonyms defined as:

house and mansion: (astrology) one of 12 equal areas into which the zodiac is divided

Other synonyms of house include planetary house, sign, sign of the zodiac, star sign.

house (noun)	mansion (noun)
play in which children take the roles of father or mother or children and pretend to interact like adults	a large and imposing house
a dwelling that serves as living quarters for one or more families	(astrology) one of 12 equal areas into which the zodiac is divided
a building in which something is sheltered or located
a building where theatrical performances or motion-picture shows can be presented
aristocratic family line
the members of a business organization that owns or operates one or more establishments
an official assembly having legislative powers
the audience gathered together in a theatre or cinema
the members of a religious community living together
a social unit living together
the management of a gambling house or casino
(astrology) one of 12 equal areas into which the zodiac is divided

house (verb)	mansion (verb)
provide someone with accomodation
contain or cover