Section E3 is on the field seating, so there is no elevation with the seats. This could potentially make it more difficult to see the stage because the tall people in front of you could obstruct your view. The good part about Section E3 is that there is a great head on view, so if your view is not obstructed by a person in front, you will have an ideal angle to see the stage.
Section 112 is part of the actual stadium seating at Soldier Field so there is more elevation and less of chance of having an obstructed view. The angle is not great from this perspective, but you should still have a clear view of the stage.
I would recommend sitting in Section E3 because an unobstructed view from this area is amazing and it is always a unique experience to be on the field during a concert, it puts you almost in the middle of the entire performance.