verb vs copula

verb and copula both are nouns.

Word	Noun	Adjective	Verb	Adverb
verb	Yes	No	No	No
copula	Yes	No	No	No

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

verb: a content word that denotes an action, occurrence, or state of existence
copula: an equating verb (such as `be' or `become') that links the subject with the complement of a sentence

verb (noun)	copula (noun)
a content word that denotes an action, occurrence, or state of existence	an equating verb (such as `be' or `become') that links the subject with the complement of a sentence
the word class that serves as the predicate of a sentence