overmuch vs excess

overmuch and excess both are nouns.

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

As nouns, excess is a hyponym of overmuch; that is, excess is a word with a more specific, narrower meaning than overmuch:

Other hyponyms of overmuch include nimiety, surplus, surplusage, glut, oversupply, surfeit, bellyful.

overmuch (noun)	excess (noun)
a quantity that is more than what is appropriate	excessive indulgence
	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

overmuch (adjective)	excess (adjective)
very great in quantity; overabundant	more than is needed, desired, or required

overmuch (adverb)	excess (adverb)
more than necessary