overmuchness vs excess

overmuchness and excess both are nouns.

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

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

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

overmuchness (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

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