My wife has a Velotric Discover 1 and I have a Ride1Up Series 500. Both are rear hub motors and cadence sensors. Very different riding experiences.
Think of cruise control in a car. Suppose in your car you have the cruise set to 60 mph then tap the brake to slow down. When you hit the resume button the car will accelerate to 60mph. That is kind of like the Velotric, only the PAS levels must factor in not only the speed but the power as a set point. You can see this on the display in power output mode. Once the set point is reached, the power output drops to close to 0.0. You can pedal to go faster but get no help from the motor. There are 5 PAS levels on my controller, but no user adjustability.
The Series 500 is very different, and I struggle to explain it. It seems that each PAS level has a maximum %output, but the actual output is proportional on both sides of the set point. At least that is how I would explain it. A much more natural feel when changing PAS levels. Ride1Up also allows the user to change the number of PAS level (up to 9) and change the %output at each.
This is not to say that the Velotric is inferior in any way. Just depends on what you like. I enjoy riding both bikes.