Blackbody radiation vs spectroscopy If a body (eg a metal) is glowing red hot then its temperature can be approximated solely based on the colour. But what if that colour is not due to blackbody radiation but due to excitation of electrons? Would temperature still be the same?
 A: There is a difference between thermal radiation, arising from material where the populations of excited states in atoms/ions and the distribution of particle speeds can be characterized by a temperature, and blackbody radiation, where all those things are true plus the radiation field is in equilibrium with the matter.
Colour refers here to a perception. It is possible to recreate the colour experienced by the eye due to a continuous blackbody spectrum with discrete emission lines at a range of frequencies. Whether that could be done at exactly the same temperature is a question about the composition of the material, the exact atomic physics of the transitions and the physiology of the eye.
However, one obvious difference that would distinguish the two would be the intensity of light. The blackbody spectrum is the maximum that can be produced by a thermal emitter at any temperature. Thus any thermal source which recreated the colour of a blackbody at a similar temperature would be less intense; or if of similar intensity, would have to be hotter.
