however vs all the same

however and all the same both are adverbs.

Word	Noun	Adjective	Verb	Adverb
however	No	No	No	Yes
all the same	No	No	No	Yes

As adverbs, however and all the same are synonyms defined as:

however and all the same: despite anything to the contrary (usually preceding a concession)

Other synonyms of however include at the same time, even so, nevertheless, nonetheless, notwithstanding, still, withal, yet.

however (adverb)	all the same (adverb)
despite anything to the contrary (usually preceding a concession)	despite anything to the contrary (usually preceding a concession)
in whatever way or manner
to whatever degree or extent
by contrast; on the other hand