percent vs vacancy rate

percent and vacancy rate both are nouns.

Word	Noun	Adjective	Verb	Adverb
percent	Yes	No	No	No
vacancy rate	Yes	No	No	No

As nouns, vacancy rate is a hyponym of percent; that is, vacancy rate is a word with a more specific, narrower meaning than percent:

percent: a proportion in relation to a whole (which is usually the amount per hundred); ten percent
vacancy rate: the percentage of all rental units (as in hotels) that are unoccupied or not rented at a given time

Other hyponyms of percent include absentee rate, occupancy rate, unemployment rate.

percent (noun)	vacancy rate (noun)
a proportion in relation to a whole (which is usually the amount per hundred); ten percent	the percentage of all rental units (as in hotels) that are unoccupied or not rented at a given time