40 years of heat, Roberto Cavalli by Mert & Marcus for V Magazine
The invisible cool, Martin Margiela, entrance to his exhibition at Antwerp's Mode Museum, 2009
Both hot and cool make the news and the type of photo is often an indicator. Hot is typically in color, cool is often in black and white. Nowness and The Moment emphasize colorful hotness with the occasional black and white cool while The Imagist stays mostly black and white with occasional color.
"Cool" = cigarettes as accessories (really?). The Imagist explains relevant fashion - "in sync with contemporary art values."
The Impossible Cool uses largely black and white photos of the roster of cool. Yet what is so interesting is the notion of "impossible," as if cool is unattainable. Cool can never be something one actively seeks or aims for. Cool is never discussed or supported, making it seem impossible to attain until we can glimpse it in full glory and are reminded of its ease.
Seek, and you will find. I searched Fashion / Art, Hot / Cool and this is what I found at Net-A-Porter and Artforum. Apparently "Hot" is colors and celebrities, "Cool" is black and Norweigen.