[関「かん」]して => About A, With relation to A N3
Considering, Concerning
に[対「たい」]して/に[対「たい」]しては => In response to (topic) A, in regards to A, considering A, in contrast to A N3
Reason, Result, Response
に[対「たい」]して/に[対「たい」]しては => In response to (topic) A, in regards to A, considering A, in contrast to A N2
Reason, Result, Response