head covering vs garment

head covering and garment both are nouns.

Word	Noun	Adjective	Verb	Adverb
head covering	Yes	No	No	No
garment	Yes	No	Yes	No

As nouns, garment is a hypernym of head covering; that is, garment is a word with a broader meaning than head covering:

head covering (noun)	garment (noun)
a garment that covers the head and face	an article of clothing

head covering (verb)	garment (verb)
	provide with clothes or put clothes on