superbly vs marvelously

superbly and marvelously both are adverbs.

Word	Noun	Adjective	Verb	Adverb
superbly	No	No	No	Yes
marvelously	No	No	No	Yes

As adverbs, superbly and marvelously are synonyms defined as:

Other synonyms of superbly include marvellously, terrifically, toppingly, wonderfully, wondrous, wondrously.

superbly (adverb)	marvelously (adverb)
(used as an intensifier) excellently	(used as an intensifier) excellently