Power level is the same as "punch" or "initial drive" - how quickly the throttle comes on. Often it is just a case of what the minimum amount of throttle is. ie: when you first pull the trigger is is 5% or 15% (or what ever it is set to), but in some ESC's it can also be a little bit of exponential built in, the throttle comes on harder through the range, not just initial. Pretty sure the fleta is just initial/punch.
Drive frequency is how many times per second that the ESC sends a power(voltage) pulse. At full throttle, it is fixed/constant - simple pass through of maximum. At partial throttle, it can vary, higher frequency = more often, therefore smoother. But also means the ESC is doing more "work" hence will run hotter.