robe vs apparel

robe and apparel both are nouns.

Word	Noun	Adjective	Verb	Adverb
robe	Yes	No	Yes	No
apparel	Yes	No	Yes	No

As verbs, apparel is a hypernym of robe; that is, apparel is a word with a broader meaning than robe:

Other hypernyms of robe include clothe, dress, enclothe, fit out, garb, garment, habilitate, raiment, tog.

robe (noun)	apparel (noun)
any loose flowing garment	clothing in general
outerwear consisting of a long flowing garment used for official or ceremonial occasions

robe (verb)	apparel (verb)
clothe formally; especially in ecclesiastical robes	provide with clothes or put clothes on
cover as if with clothing