As adverbs the difference between arguably and admittedly
is that arguably is as can be supported or proven by sound logical deduction, evidence, and precedent while admittedly is as is acknowledged to be true; by general admission; confessedly.
As adverbs the difference between inevitably and admittedly
is that inevitably is in a manner that is impossible to avoid or prevent while admittedly is as is acknowledged to be true; by general admission; confessedly.