Most of us would recognize the MCU as the most important difference to ask about the difference.
2017 has MCU1 and could have AP2.0 hardware. Depending on the month the 2018 was built (specifically) March 2018 and after, it will have MUC2 and AP2.5 hardware. A significant improvement in features and center screen performance along with features unavailable to the 2017 (until that one is upgraded to the Infotainment Upgrade - cost $ 2500.
Battery and motor are the same if the batteries are the same size.
Seats, don't have a clue.
I don't think there exist a side by side comparison of all feature or like/differences between the cars. Sorry.