If I understand it correctly, net expected chips won, is what you can expect if you run this sitation millions of times. For example if you get 1000 chips all in preflop with AA vs 77 you will have about 80% to win the hand. Your net expected chips won will in this case be +800 chips.
You will of course never win 800 chips in one "race", as there is only three outcomes. You will either win or lose 1000 chips (With the exeption of the very rare split pot). This is what chip won/lost measures. Chips won in this case will be either + or - 1000 chips or zero if it is a split pot.
I hope someone with more knowledge than me comments.
Ps. I agree the poster above that you you need to really get to know you tool before you use it. You should also have a big sample before you read to mutch out of it.
Just my 2 cents
Sprockett