mankind vs group

mankind and group both are nouns.

Word	Noun	Adjective	Verb	Adverb
mankind	Yes	No	No	No
group	Yes	No	Yes	No

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

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

mankind (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

mankind (verb)	group (verb)
	arrange into a group or groups
	form a group or group together