Taste.
But I'll say, if you're a person that doesn't like to spend 3x longer to cook your food, don't get a pellet smoker.
I'm good spending an entire Saturday sitting on the deck drinking beers while the smoker does its job on a pork shoulder/ribs/brisket/whatever. But even cooking a chicken breast is longer if you want to really get that smoke flavor. I threw a few breasts on the other day and left to run to the butcher before they closed. Ended up running a few more places and when the alarm went off, I texted my wife to take them off.
It isn't a good "grill" for a person without patience.
The other thing I seem to need to explain to my wife every time I cook is done temperature over time.
The FDA recommends your chicken temperature to reach 165°F. These tips will make sure you're getting the right chicken cooking temp.
blog.thermoworks.com