thus far vs up to now

thus far and up to now both are adverbs.

Word	Noun	Adjective	Verb	Adverb
thus far	No	No	No	Yes
up to now	No	No	No	Yes

As adverbs, thus far and up to now are synonyms defined as:

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

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

thus far (adverb)	up to now (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
	prior to the present time