workwear vs work-shirt

workwear and work-shirt both are nouns.

Word	Noun	Adjective	Verb	Adverb
workwear	Yes	No	No	No
work-shirt	Yes	No	No	No

As nouns, work-shirt is a hyponym of workwear; that is, work-shirt is a word with a more specific, narrower meaning than workwear:

Other hyponyms of workwear include blue jeans, denim, jeans.

workwear (noun)	work-shirt (noun)
heavy-duty clothes for manual or physical work	heavy-duty shirts worn for manual or physical work