What is the difference between にしては and としては?


I know they are both used for comparisons, i.e. "as X...", "for a X....", but
I don't understand the difference between them.




I think にしては is close to "considering" and としては is close to "as".

For example, 彼は英語の先生にしては、優秀だ (He is talented considering he is a English
teacher.) implies he has an ability other than English, but 彼は英語の先生としては、優秀だ
(He is talented as a English teacher.) implies the ability of teaching
English.

