approximately vs more or less

approximately and more or less both are adverbs.

Word	Noun	Adjective	Verb	Adverb
approximately	No	No	No	Yes
more or less	No	No	No	Yes

As adverbs, approximately and more or less are synonyms defined as:

approximately and more or less: (of quantities) imprecise but fairly close to correct

Other synonyms of approximately include about, around, close to, just about, or so, roughly, some.

approximately (adverb)	more or less (adverb)
(of quantities) imprecise but fairly close to correct	(of quantities) imprecise but fairly close to correct
	to a small degree or extent