namesake vs someone

namesake and someone both are nouns.

Word	Noun	Adjective	Verb	Adverb
namesake	Yes	No	No	No
someone	Yes	No	No	No

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

namesake: a person with the same name as another
someone: a human being; person, singular, assertive existential pronoun; pronoun, person, singular; quantifier: assertive existential

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

namesake (noun)	someone (noun)
a person with the same name as another	a human being; person, singular, assertive existential pronoun; pronoun, person, singular; quantifier: assertive existential