Question

What is meant by luminous and nonluminous flames?

Answer 1

A non-luminous flame undergoes complete combustion as it draws much more oxygen and gets much hotter. There are several "zones" within a non-luminous flame, and each zone has a different temperature. The outermost zone of the flame is blue in colour and it is the hottest part. A luminous flame is [by comparison] a bright, light emiting, usually yellow, flame. For example, if you light a match and watch it burn, this is a luminous flame. 
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Answer 2

A blue coloured flame which undergo complete combustion and gives off less light is non luminous flame.
Whereas an yellow coloured flame which do not undergo complete combustion and gives off more light is luminous flame
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