frown on vs frown upon

frown on and frown upon both are verbs.

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

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

frown on (verb)	frown upon (verb)
look disapprovingly upon	look disapprovingly upon