Either can extract vehicle data by calculation for MQB car, or via any other source for immo data calculations. If you have other high-end programmers, buy VVDI2; if you don’t have any, buy VVDI Key Tool Plus.
Xhorse VVDI Key Tool Plus is the better purchase now, everyone has moved to tablet tools. It still needs more updates to be able to cover everything it replaces, but they have been updating it like crazy. I’m fairly happy with it. Xhorse is going to throw supports at Key Tool Plus, and all in 1 tablet is what there all is going. 100% buy KTP, and it saves money in long the run.
Functions are different, hard to say which is better. Xhorse VVDI Key Tool Plus is a key tool, so it emphasizes key matching. While VVDI series like VVDI2, VVDI Prog may have specialized functions like coding, refreshing etc. that the tablet may not support. I would rather say which better suits you.