emphatically vs decidedly

emphatically and decidedly both are adverbs.

Word	Noun	Adjective	Verb	Adverb
emphatically	No	No	No	Yes
decidedly	No	No	No	Yes

As adverbs, emphatically and decidedly are synonyms defined as:

Other synonyms of emphatically include by all odds, definitely, in spades, unquestionably.

emphatically (adverb)	decidedly (adverb)
without question and beyond doubt	without question and beyond doubt