loath vs averse

loath and averse both are adjectives.

Word	Noun	Adjective	Verb	Adverb
loath	No	Yes	No	No
averse	No	Yes	No	No

As adjectives, loath and averse are synonyms defined as:

Other synonyms of loath include antipathetic, antipathetical, indisposed, loth.

loath (adjective)	averse (adjective)
(usually followed by `to') strongly opposed	(usually followed by `to') strongly opposed
unwillingness to do something contrary to your custom