eveningwear vs evening clothes

eveningwear and evening clothes both are nouns.

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

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

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

Other synonyms of eveningwear include evening dress, formalwear.

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