copula vs verb

copula and verb both are nouns.

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

As nouns, verb is a hypernym of copula; that is, verb is a word with a broader meaning than copula:

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

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