populace vs people

populace and people both are nouns.

Word	Noun	Adjective	Verb	Adverb
populace	Yes	No	No	No
people	Yes	No	Yes	No

As nouns, people is a hypernym of populace; that is, people is a word with a broader meaning than populace:

populace: people in general considered as a whole
people: (plural) any group of human beings (men or women or children) collectively

populace (noun)	people (noun)
people in general considered as a whole	(plural) any group of human beings (men or women or children) collectively
	the body of citizens of a state or country
	members of a family line
	the common people generally

populace (verb)	people (verb)
	fill with people
	furnish with people