As adjectives the difference between excess and sentimental
is that
excess is more than is normal, necessary or specified while
sentimental is characterized by sentiment, sentimentality or excess emotion.
As a noun excess
is the state of surpassing or going beyond limits; the being of a measure beyond sufficiency, necessity, or duty; that which exceeds what is usual or proper; immoderateness; superfluity; superabundance; extravagance; as, an excess of provisions or of light.