It comes down to how the heat is distributed. Both convection and conventional ovens are powered by gas or electricity. But the heat source in a conventional oven is. Empower your inner chef with a Thermador convection oven. Our wall ovens, gas ovens and conventional ovens offer the largest capacity and professional quality. A new oven is always a welcome addition to any kitchen. Heres how to tell the difference between convection and conventional and maximize the. Conventional ovens have become an essential modern cooking device, providing a wide variety of functions that assist in food preparation. The general purpose of the. Conventional OvensConvection ovens allow for even, fast cooking because the temperature stays more consistent, whereas conventional ovens can have pockets of warmer or colder air. Hot air rises, so when cooking food on both racks, dishes on the bottom rack may undercook while the food on top burns, explains Allison Eckelkamp, media representative at General Electric.