The quesadillas have, like most frozen foods in the grocery store, their calories primarily come from highly processed corn/wheat. I suspect that's a big part of the issue.
I'm not sure what the exact definition of "processed" being used is though so I can't say for certain. But both are being stripped of outer layer, mixed with water and cooked. I suppose you need a tablespoon or so of oil to cook the tortillas but I'm assuming you're sautéing the veggies for the stir fry in oil too.
I just don't get what processed means in this context.