unemployment rate vs percentage

unemployment rate and percentage both are nouns.

Word	Noun	Adjective	Verb	Adverb
unemployment rate	Yes	No	No	No
percentage	Yes	No	No	No

As nouns, percentage is a hypernym of unemployment rate; that is, percentage is a word with a broader meaning than unemployment rate:

unemployment rate: the percentage of the work force that is unemployed at any given date
percentage: a proportion in relation to a whole (which is usually the amount per hundred); ten percent

Other hypernyms of unemployment rate include pct, per centum, percent.

unemployment rate (noun)	percentage (noun)
the percentage of the work force that is unemployed at any given date	assets belonging to or due to or contributed by an individual person or group
	a proportion in relation to a whole (which is usually the amount per hundred); ten percent