The type of oven you use plays a key role in how the food will turn out. Two types of ovens are convection ovens and thermal ovens. The main difference between the two is that convection ovens actively move the heat around the food whereas thermal ovens simply allow it to circulate passively.
The main difference between convection and thermal ovens is how they heat the food. Convection ovens circulate hot air using a fan so that the heat is constantly moving around at an even rate. Thermal ovens also use hot air to heat food, but without the assistance of a fan, the heat is not uniform and may become blocked by objects in the oven.
Because they circulate hot air evenly throughout the oven, convection ovens tend to cook food more evenly and in less time. The constant movement of heat enables these ovens to use less energy as well. In a thermal oven, the air is relatively still, which can lead to uneven cooking of foods. This is because hot air rises, so the highest temperature is found near the top of the oven while the bottom may be significantly cooler.
Using a thermal oven can be risky if you want consistent results. For instance, if you're baking cookies and one side of the oven is hotter than the other, one half of the pan may be done in 10 minutes while the other half will still be gooey. In a convection oven the circulating air will enable all of your food to achieve the same results in the same amount of time.
Convection ovens are not only more consistent than thermal ovens but also quicker because of the constantly circulating air that blows heat directly onto the baking food. The fan in a convection oven helps in another way. By drawing air over the motor, it helps to prevent overheating.
Because of their many advantages over conventional thermal ovens, convection oven types are becoming increasingly popular whereas the once widespread thermal ovens are becoming increasingly difficult to find.