abuse vs mistreat

abuse is a noun but mistreat is not a noun.

Word	Noun	Adjective	Verb	Adverb
abuse	Yes	No	Yes	No
mistreat	No	No	Yes	No

As verbs, abuse and mistreat are synonyms defined as:

Other synonyms of abuse include ill-treat, ill-use, maltreat, step.

abuse (noun)	mistreat (noun)
improper or excessive use
cruel or inhumane treatment
a rude expression intended to offend or hurt

abuse (verb)	mistreat (verb)
change the inherent purpose or function of something	treat badly
use wrongly or improperly or excessively
use foul or abusive language towards
treat badly