It’s different. I play Road to the Show mostly. In 17, you could max out your player skills and become a dominant broheim. In 18, you pick a player archetype. For me, I’m playing as a short stop with the Wizard player type. Means my hard cap on fielding, reaction, arm accuracy are 99 (still you will have soft caps of day 80 that you need to train to get the soft cap moving towards the hard cap). But my hard cap for power iirc is only 70. Still, at 70 in my rookie year in the big leagues I got 14 homers, but my main focus was getting on base.
The way you skill up is execution. For example, you improve plate discipline if you lay off a ball pitch. But, if you strike out the discipline rating regresses. If I pop up my contact rating goes down. But if I pick the right pitch and time it right I will increase my contact.
So you’re rewarded for your in game performance which I like. That’s the biggest change I see. Graphically etc it is the same as 17.