1x vs 2x difference in climbing?

Hey Guys,

I am needing to replace my Marin DSX 2 and looking at a Marin Four Corners 1.

The DSX had a 1x42T and 10-51T while the Four Corners has a 2x9 with 46/32T and an 11-36T.

My main question is what kind of difference should I be expecting? Particularly on steep/long climbs.

Cheers