roundhead vs somebody

roundhead and somebody both are nouns.

Word	Noun	Adjective	Verb	Adverb
roundhead	Yes	No	No	No
somebody	Yes	No	No	No

As nouns, somebody is a hypernym of roundhead; that is, somebody is a word with a broader meaning than roundhead:

roundhead: a brachycephalic person
somebody: a human being; person, singular, assertive existential pronoun; pronoun, person, singular; quantifier: assertive existential

Other hypernyms of roundhead include individual, mortal, person, someone, soul.

roundhead (noun)	somebody (noun)
a brachycephalic person	a human being; person, singular, assertive existential pronoun; pronoun, person, singular; quantifier: assertive existential