The main difference:
1. Scope: PPT more compatible.
2. Synchronization: Keynote Icloud synchronization between different devices is better.
3. Animated: Keynote ready-made gorgeous.
4. Openness: PPT can insert a variety of third-party software and programs.
Overall, if I have a lot of time to prepare a speech, I will use PPT. If you have time to come up with some harsh results, I use Keynote.