some vs approximately

some is an adjective but approximately is not an adjective.

Word	Noun	Adjective	Verb	Adverb
some	No	Yes	No	Yes
approximately	No	No	No	Yes

As adverbs, some and approximately are synonyms defined as:

some and approximately: (of quantities) imprecise but fairly close to correct

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

some (adjective)	approximately (adjective)
(quantifier) used with either mass nouns or plural count nouns to indicate an unspecified number or quantity
remarkable
relatively many but unspecified in number

some (adverb)	approximately (adverb)
(of quantities) imprecise but fairly close to correct	(of quantities) imprecise but fairly close to correct