approximation vs version

approximation and version both are nouns.

Word	Noun	Adjective	Verb	Adverb
approximation	Yes	No	No	No
version	Yes	No	No	No

As nouns, version is a hypernym of approximation; that is, version is a word with a broader meaning than approximation:

approximation (noun)	version (noun)
the act of bringing near or bringing together especially the cut edges of tissue	manual turning of a fetus in the uterus (usually to aid delivery)
the quality of coming near to identity (especially close in quantity)	a mental representation of the meaning or significance of something
an approximate calculation of quantity or degree or worth	something a little different from others of the same type
an imprecise or incomplete account	a written communication in a second language having the same meaning as the written communication in a first language
	an interpretation of a matter from a particular viewpoint
	a written work (as a novel) that has been recast in a new form