mansion vs palace

mansion and palace both are nouns.

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

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

Other hyponyms of mansion include manor, manor house, castle, stately home, mcmansion.

mansion (noun)	palace (noun)
a large and imposing house	official residence of an exalted person (as a sovereign)
(astrology) one of 12 equal areas into which the zodiac is divided	a large and stately mansion
	a large ornate exhibition hall
	the governing group of a kingdom