evening clothes vs eveningwear

evening clothes and eveningwear both are nouns.

Word	Noun	Adjective	Verb	Adverb
evening clothes	Yes	No	No	No
eveningwear	Yes	No	No	No

As nouns, evening clothes and eveningwear are synonyms defined as:

evening clothes and eveningwear: attire to wear on formal occasions in the evening

Other synonyms of evening clothes include evening dress, formalwear.

evening clothes (noun)	eveningwear (noun)
attire to wear on formal occasions in the evening	attire to wear on formal occasions in the evening