or so vs close to

or so and close to both are adverbs.

Word	Noun	Adjective	Verb	Adverb
or so	No	No	No	Yes
close to	No	No	No	Yes

As adverbs, or so and close to are synonyms defined as:

or so and close to: (of quantities) imprecise but fairly close to correct

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

or so (adverb)	close to (adverb)
(of quantities) imprecise but fairly close to correct	(of quantities) imprecise but fairly close to correct