generation vs posterity

generation and posterity both are nouns.

Word	Noun	Adjective	Verb	Adverb
generation	Yes	No	No	No
posterity	Yes	No	No	No

As nouns, posterity is a hyponym of generation; that is, posterity is a word with a more specific, narrower meaning than generation:

generation: group of genetically related organisms constituting a single step in the line of descent
posterity: all future generations

Other hyponyms of generation include baby-boom generation, baby boom, gen X, generation X.

generation (noun)	posterity (noun)
the act of producing offspring or multiplying by such production	all future generations
the production of heat or electricity	all of the offspring of a given progenitor
a coming into being
group of genetically related organisms constituting a single step in the line of descent
all the people living at the same time or of approximately the same age
the normal time between successive generations
a stage of technological development or innovation