think of vs look upon

think of and look upon both are verbs.

Word	Noun	Adjective	Verb	Adverb
think of	No	No	Yes	No
look upon	No	No	Yes	No

As verbs, think of and look upon are synonyms defined as:

Other synonyms of think of include be known as, esteem, know as, look on, regard as, repute, take to be.

think of (verb)	look upon (verb)
keep in mind for attention or consideration	look on as or consider
look on as or consider
intend to refer to
take into consideration, have in view
choose in one's mind
devise or invent