human beings vs group

human beings and group both are nouns.

Word	Noun	Adjective	Verb	Adverb
human beings	Yes	No	No	No
group	Yes	No	Yes	No

As nouns, group is a hypernym of human beings; that is, group is a word with a broader meaning than human beings:

Other hypernyms of human beings include grouping, homo, human, human being, man.

human beings (noun)	group (noun)
all of the living human inhabitants of the earth	any number of entities (members) considered as a unit
	a set that is closed, associative, has an identity element and every element has an inverse
	(chemistry) two or more atoms bound together as a single unit and forming part of a molecule

human beings (verb)	group (verb)
	arrange into a group or groups
	form a group or group together