Here we can't see the difference between average applied force and average net force.
Sadly, we can't see the tables, but we can answer in a general form.
1) We define average applied force as a force that we apply on a given object.
For example, if we have a box on the ground and we push it horizontally with 50N of force, the average force applied will be 50N.
While average net force refers to the sum of all the forces applied in the box.
Let's return to the previous example.
Now assume that you do not push the box exactly horizontally, but there is a slight angle upwards.
Then there will be a component of the force that is horizontal and a component that is vertical, and is likely that the vertical component of the force is canceled by the weight (also a force) of the box.
Thus the applied force can still be equal to 50N, but the net force may be a little bit smaller.
This is why these average forces differ.
2) Why should the average net force be used to get the acceleration?.
Again, if some part of the applied force is canceled (by the weight or another force) then that force does not affect the object in any way. This is why we need to use the average net force to compute the acceleration.
If you want to learn more, you can read:
https://brainly.com/question/13410291
