ill-bred vs underbred

ill-bred and underbred both are adjectives.

Word	Noun	Adjective	Verb	Adverb
ill-bred	No	Yes	No	No
underbred	No	Yes	No	No

As adjectives, ill-bred and underbred are synonyms defined as:

Other synonyms of ill-bred include bounderish, lowbred, rude, yokelish.

ill-bred (adjective)	underbred (adjective)
(of persons) lacking in refinement or grace	of inferior or mixed breed
	(of persons) lacking in refinement or grace