austere vs ascetical

austere and ascetical both are adjectives.

Word	Noun	Adjective	Verb	Adverb
austere	No	Yes	No	No
ascetical	No	Yes	No	No

As adjectives, austere and ascetical are synonyms defined as:

Other synonyms of austere include ascetic, spartan.

austere (adjective)	ascetical (adjective)
practicing great self-denial	pertaining to or characteristic of an ascetic or the practice of rigorous self-discipline
of a stern or strict bearing or demeanor; forbidding in aspect	practicing great self-denial
severely simple