too vs excessively

too and excessively both are adverbs.

Word	Noun	Adjective	Verb	Adverb
too	No	No	No	Yes
excessively	No	No	No	Yes

As adverbs, too and excessively are synonyms defined as:

Other synonyms of too include overly, to a fault.

too (adverb)	excessively (adverb)
to a degree exceeding normal or proper limits	to a degree exceeding normal or proper limits
in addition