side dish vs entremets

side dish and entremets both are nouns.

Word	Noun	Adjective	Verb	Adverb
side dish	Yes	No	No	No
entremets	Yes	No	No	No

As nouns, side dish and entremets are synonyms defined as:

side dish and entremets: a dish that is served with, but is subordinate to, a main course

Other synonyms of side dish include side order.

side dish (noun)	entremets (noun)
a dish that is served with, but is subordinate to, a main course	a dish that is served with, but is subordinate to, a main course