sweep-second vs sweep hand

sweep-second and sweep hand both are nouns.

Word	Noun	Adjective	Verb	Adverb
sweep-second	Yes	No	No	No
sweep hand	Yes	No	No	No

As nouns, sweep-second and sweep hand are synonyms defined as:

sweep-second and sweep hand: a second hand that is mounted on the same center as the hour and minute hand and is read on the minutes

sweep-second (noun)	sweep hand (noun)
a second hand that is mounted on the same center as the hour and minute hand and is read on the minutes	a second hand that is mounted on the same center as the hour and minute hand and is read on the minutes