What is the difference between thermal and electromagnetic radiation?

Question

In my understanding thermal radiation and electromagnetic radiation is same, for example suppose we heat up a knife to high temperature then it glows red. This means the thermal radiation / electromagnetic radiation is red coloured light , however in this answer it was noted in the comments that thermal radiation and electromagnetic radiation are not always the same. Examples of bio luminescence and lasers were given.

However, now I do not understand the fundamental difference between them. If thermal radiation is basically just photons, then what is electromagnetic radiation consisting of?

Related

Answer 1

It goes like this: all thermal radiation is electromagnetic radiation, but not all electromagnetic radiation is thermal radiation. In that sense electromagnetic is the type of radiation, thermal is the cause of the radiation. There are, of course, other sources of electromagnetic radiation, besides thermal. Compare an incandescent light bulb (thermal radiation) to an LED (recombination radiation).