As always, 2 players, same position, tall, foot etc. The first will score 40 goals having 5*. The 2nd player, you will train him till 9* and will not appear in the 1/2 of the matches, rarely you will see his name and will score 4 goals with 9*.

I.P.

Internal Programming, with min/max of, contribution so how % of influence have and how many times you see his name during matches if you set him in the 11, how effective is in shooting with min/max %, how agressive, and more things that we dont know.