Is there any difference between unintended acceleration and high idle?

Yes. The difference is a high idle can be controlled by pressing the brake. Meaning if you have a high idle then the vehicle may roll or even accelerate when you remove your foot from the brake but you can reapply the brake and stop the vehicle.

Unintended acceleration is something that the vehicle accelerates on its own at an unexpected time and it is hard or not possible to slow the vehicle down.

Many people have used this term incorrectly and it has become more general then what it really is.

Do you have a high idle? If so, I would start with checking for a vacuum leak.

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Let us know. Thanks

Will a high idle wear the brake pads fast? And how can high idle be a danger?

High idle will not wear the pads unless you are just riding the brakes a lot when traveling at slow speeds. So if the idle is high enough that you need to keep steady pressure on the brake pedal when driving slowly then it could have an effect on them.

High idle is not dangerous unless you can't control the vehicle or that it is so high that when you remove your foot from the brake the car takes off. When you remove your foot from the brake the vehicle should move forward but it should not accelerate quickly.

Let me know if you have questions. Thanks

Actually the car is accelerating but the speed is going up at a normal rate. For the driver though she said she is comfortable to drive with it but i am pretty sure she is riding the brakes.
How does it occur this high idle?i guess it has the similarities of stuck gas pedal right?

Here is a guide that will help with high idle in general:

https://www.2carpros.com/articles/engine-idles-too-high

The idea could be the same as a stuck pedal but it is unlikely to be the issue unless the throttle cable is sticking.

However, the idea is the idle is high due to extra air or fuel entering the engine raising the idle. Or the idle control is not correct. On this vehicle it appears the DME controls the idle control valve. Usually when these fail the engine will stall as they stick closed.

https://www.2carpros.com/articles/idle-air-control-valve-service

I attached the info below on this which should illustrate this better.