enter upon vs enter

enter upon and enter both are verbs.

Word	Noun	Adjective	Verb	Adverb
enter upon	No	No	Yes	No
enter	No	No	Yes	No

enter upon (verb)	enter (verb)
take possession of	set out on (an enterprise or subject of study)
	make a record of; set down in permanent form
	become a participant; be involved in
	put or introduce into something
	come on stage
	to come or go into
	take on duties or office
	register formally as a participant or member
	be or play a part of or in