A: In terms of the working environment and level of reliability. An high quality Oven PCBA is specifically made to work for a long time in a place that's very warm, sometimes even wet, inside a big kitchen machine called an oven. It makes use of parts that can tolerate higher temperatures, it has protective coatings that can withstand conformal temperatures, and the arrangement is such that it promotes heat dissipation. And it has a very strong focus on safely controlling a very high power heating element, and most standard electronics don’t have to deal with that.
The key challenge is getting the fan motor to work together with the heating elements. The PCBA design must have a motor drive circuit and more complex control algorithms for regulating both the fan speed and heat.