Originally Posted by RChung

Not much, which is kind of interesting--pedals are a "noisier" platform, which is why pedal-based power meters took much longer to come to the market. The crank can also be noisy (especially the right crank) but pedal orientation matters, plus you have less room to work with.

That said, the added noise in a pedal system means that the "instantaneous" power readings from them can require more averaging even if they're close over a full revolution. You can sometimes see this in max 1 second readings. (This is why I don't pay much attention to max power unless I know what power meter it was measured on--and even then I don't pay a huge amount of attention).