excess vs surplus

excess and surplus both are nouns.

Word	Noun	Adjective	Verb	Adverb
excess	Yes	Yes	No	No
surplus	Yes	Yes	No	No

As adjectives, excess and surplus are synonyms defined as:

Other synonyms of excess include extra, redundant, spare, supererogatory, superfluous, supernumerary.

As nouns, excess and surplus are synonyms defined as:

Other synonyms of excess include nimiety, surplusage.

excess (noun)	surplus (noun)
excessive indulgence	a quantity much larger than is needed
immoderation as a consequence of going beyond sufficient or permitted limits
a quantity much larger than is needed
the state of being more than full

excess (adjective)	surplus (adjective)
more than is needed, desired, or required	more than is needed, desired, or required