Difference between rolls wouldn't work because a person could roll a 1 with -1 Strength and no Athletics while the other rolls 20 with +5 Athletics, thus throwing them 25 feet, or something similar. On the other hand, a Strength 10 person could wind up shoving an ogre 15 feet just because the ogre rolled a 1. [...].
I wasn't trying to say that an enemy should be shoved Equal to the difference between the rolls, just that the difference could
affect the distance shoved.
E.g., shover's roll is equal to the defender's roll or up to 9 higher - shove 5 feet
shover's roll is 10-19 higher - shove 10 feet
shover's roll is 20-29 higher - shove 15 feet
shover's roll is somehow 30+ higher - shove 20 feet
Something like that. This is just an example and the exact numbers could be tweaked. This could also be affected by size differences in characters (e.g, creatures one size larger get shoved 5 less feet) and/or could be your check compared to the enemy taking 10 on the Athletics skill.
