Difference between Luminous and non luminous zone ?

Luminous zone:-

The luminous zone is the brightest and middle zone of a flame. In this zone, oxygen availability is not sufficient. The luminous zone is a yellow flame zone having a modest temperature.

Non-luminous zone:-

The zone of complete combustion is known as a non-luminous zone. In this zone complete combustion of fuel takes place due to the availability of sufficient oxygen. This is the outermost zone of a flame with the highest temperature.