more or less vs approximately

more or less and approximately both are adverbs.

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

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

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

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

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