til now vs so far

til now and so far both are adverbs.

Word	Noun	Adjective	Verb	Adverb
til now	No	No	No	Yes
so far	No	No	No	Yes

As adverbs, til now and so far are synonyms defined as:

til now and so far: used in negative statement to describe a situation that has existed up to this point or up to the present time

Other synonyms of til now include as yet, heretofore, hitherto, thus far, until now, up to now, yet.

til now (adverb)	so far (adverb)
used in negative statement to describe a situation that has existed up to this point or up to the present time	used in negative statement to describe a situation that has existed up to this point or up to the present time
	used after a superlative
	to the degree or extent that