Easy: makes the game a little easy but doesn’t change the gameplay a lot.
Hard, Normal: Makes game better while not changing the pes 17 gameplay, but only adding some fouls and better reactions.
Hard, Legacy: changes many things in gameplay. (Not recommended for people who enjoy original gameplay.)
Legacy changes: Ball, speed, gk, ai & …
Alternative gameplay: a gameplay for people who like to have a fun arcade pes that has aggression and speed and is not so hard.