hitherto vs til now

hitherto and til now both are adverbs.

Word	Noun	Adjective	Verb	Adverb
hitherto	No	No	No	Yes
til now	No	No	No	Yes

As adverbs, hitherto and til now are synonyms defined as:

hitherto and til 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 hitherto include as yet, heretofore, so far, thus far, until now, up to now, yet.

hitherto (adverb)	til 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