White person vs Caucasian

White person and Caucasian both are nouns.

Word	Noun	Adjective	Verb	Adverb
White person	Yes	No	No	No
Caucasian	Yes	Yes	No	No

As nouns, White person and Caucasian are synonyms defined as:

White person and Caucasian: a person of European descent with a light-skinned or pale complexion

Other synonyms of White person include White.

White person (noun)	Caucasian (noun)
a person of European descent with a light-skinned or pale complexion	a number of languages spoken in the Caucasus that are unrelated to languages spoken elsewhere
	a person of European descent with a light-skinned or pale complexion

White person (adjective)	Caucasian (adjective)
	of or relating to the geographical region of Caucasia
	of or relating to Caucasian people