improper vs unconventional

improper and unconventional both are adjectives.

Word	Noun	Adjective	Verb	Adverb
improper	No	Yes	No	No
unconventional	No	Yes	No	No

As adjectives, improper and unconventional are synonyms defined as:

improper and unconventional: not conforming to legality, moral law, or social convention

Other synonyms of improper include unlawful.

improper (adjective)	unconventional (adjective)
not suitable or right or appropriate	not conforming to accepted rules or standards
not appropriate for a purpose or occasion	not conventional or conformist
not conforming to legality, moral law, or social convention	not conforming to legality, moral law, or social convention