person of colour vs someone

person of colour and someone both are nouns.

Word	Noun	Adjective	Verb	Adverb
person of colour	Yes	No	No	No
someone	Yes	No	No	No

As nouns, someone is a hypernym of person of colour; that is, someone is a word with a broader meaning than person of colour:

person of colour: (formal) any non-European non-white person
someone: a human being; person, singular, assertive existential pronoun; pronoun, person, singular; quantifier: assertive existential

Other hypernyms of person of colour include individual, mortal, person, somebody, soul.

person of colour (noun)	someone (noun)
(formal) any non-European non-white person	a human being; person, singular, assertive existential pronoun; pronoun, person, singular; quantifier: assertive existential