2” wider wheel. 1” on the inside (which shows up on the backspace), one inch on the outside. You lose 1” to the springs, and 1” to the quarter.
The offset on both wheels is zero.
And for the OP, if you have stock spring locations and wheel tubs, the widest tire you’re going to get in there is a 275 unless the rear of the car is jacked way up in the air. Which makes the 15x10 kind of a waste. If you have spring offset, or a relocation with mini-tubs, carry on.
