civvies vs civilian clothing

civvies and civilian clothing both are nouns.

Word	Noun	Adjective	Verb	Adverb
civvies	Yes	No	No	No
civilian clothing	Yes	No	No	No

As nouns, civilian clothing is a hypernym of civvies; that is, civilian clothing is a word with a broader meaning than civvies:

civvies: civilian garb as opposed to a military uniform
civilian clothing: ordinary clothing as distinguished from uniforms, work clothes, clerical garb, etc.

Other hypernyms of civvies include civilian dress, civilian garb, plain clothes.

civvies (noun)	civilian clothing (noun)
civilian garb as opposed to a military uniform	ordinary clothing as distinguished from uniforms, work clothes, clerical garb, etc.