Are uses different between HR and Power?

Physiology people, do I get the same benefit from having a HR in the tempo zone during an interval with my power not being in that zone. For clarification, if I do a 30+ min tempo interval on trails and my HR is in the tempo zone when I’m descending, do I get the same (or close to the same) aerobic training stimulus as if I was pedaling? I was wondering because Frank Overton advices doing tempo mtb rides were your NP for the interval is at tempo, even though you can’t pedal for the whole time because of downhills and such.

Thanks in advance

No.

Depends on the trails you ride (as far as coasting). If you’re riding up a mountain and coasting for 10 minutes back down, probably not beneficial. If you’re riding trails where you’re coasting sometimes but pedaling most of the time, you’re still getting some benefit, but not as much as if you pedal nonstop