half-hour vs time unit

half-hour and time unit both are nouns.

Word	Noun	Adjective	Verb	Adverb
half-hour	Yes	No	No	No
time unit	Yes	No	No	No

As nouns, time unit is a hypernym of half-hour; that is, time unit is a word with a broader meaning than half-hour:

Other hypernyms of half-hour include unit of time.

half-hour (noun)	time unit (noun)
a half of an hour	a unit for measuring time periods