に[比「くら」]べて/に[比「くら」]べ => When compared to A N3
Comparison, Exchange
[一方「いっぽう」]だ => Change A continues, A does not stop N2
Miscellaneous
[一方「いっぽう」] => On one hand A, on the other, B; Although A, at the same time, B N2
Contrast,Surprise