build on vs build upon

build on and build upon both are verbs.

Word	Noun	Adjective	Verb	Adverb
build on	No	No	Yes	No
build upon	No	No	Yes	No

As verbs, build on and build upon are synonyms defined as:

Other synonyms of build on include repose on, rest on.

build on (verb)	build upon (verb)
use as a basis for theories and claims	use as a basis for theories and claims