Conventional ovens bake and roast by surrounding food with heat from the bottom of the oven cavity. Broiling food has intense heat coming from above, either in the oven, or behind a small door under the oven.
Convection ovens work basically the same as a conventional oven with the addition of a fan in the back of the oven that circulates heated air around the food in a swirling pattern. When the fan is turned on, hot air blows around the inside of the oven. It’s the fan that promotes even heating and more rapid cooking than a conventional oven.