so-so vs acceptably

so-so is an adjective but acceptably is not an adjective.

Word	Noun	Adjective	Verb	Adverb
so-so	No	Yes	No	Yes
acceptably	No	No	No	Yes

As adverbs, so-so and acceptably are synonyms defined as:

Other synonyms of so-so include tolerably.

so-so (adjective)	acceptably (adjective)
being neither good nor bad

so-so (adverb)	acceptably (adverb)
in an acceptable (but not outstanding) manner	in an acceptable (but not outstanding) manner