robe vs academic gown

robe and academic gown both are nouns.

Word	Noun	Adjective	Verb	Adverb
robe	Yes	No	Yes	No
academic gown	Yes	No	No	No

As nouns, academic gown is a hyponym of robe; that is, academic gown is a word with a more specific, narrower meaning than robe:

robe: outerwear consisting of a long flowing garment used for official or ceremonial occasions
academic gown: a gown worn by academics or judges

Other hyponyms of robe include academic robe, judge's robe, vestment.

robe (noun)	academic gown (noun)
any loose flowing garment	a gown worn by academics or judges
outerwear consisting of a long flowing garment used for official or ceremonial occasions

robe (verb)	academic gown (verb)
clothe formally; especially in ecclesiastical robes
cover as if with clothing