convection microwaves offer the quick cooking features of a microwave with the browning, crisping, and full "cook-through" of a traditional oven.
Instead of just heating the inside of the food (as regular microwaves do), a convection microwave also browns and cooks the outside of your food.
Scientifically speaking, regular microwaves emit waves that bounce around until they come in contact with food, causing water molecules to excite and generate heat, which then cooks the food.
In contrast,
convection oven technology uses a fan to force air movement and heat up the full interior of the microwave to cook food from the inside out.
That's why you can use convection microwaves to bake and roast things that would otherwise be cooked too quickly (and not thoroughly) with just a regular microwave.