VX limits the amount of custom graphics you can have, by a lot. XP Doesn't.
VX has a random dungeon generator. XP Doesn't
VX has quick event creation, which allows you to create teleport events, doors, chests, and inns with just a few clicks. XP doesn't have any quick event creation.
VX only has two layers, Tile A is the bottom, and the rest are the top. XP has three layers which you can select what tile is to be on what layer.