unattractive vs unprepossessing

unattractive and unprepossessing both are adjectives.

Word	Noun	Adjective	Verb	Adverb
unattractive	No	Yes	No	No
unprepossessing	No	Yes	No	No

unattractive (adjective)	unprepossessing (adjective)
lacking beauty or charm	creating an unfavorable or neutral first impression
lacking power to arouse interest
not appealing to the senses