The angles are very different but the WTC7 building looks like it has a very hot fire burning inside. The building from this post looks like the fire is mostly on the outer parts of the building.
Also, black smoke is probably from the plastics and artificial chair stuffing, stuff like that.
What's more, the russian building has a massive tower of black smoke. What exactly did you mean that there wasn't any? I see much more in this russian building than in the WTC7 pics you posted.
Also, the color isn't necessarily white. It's hard to tell and I think inconclusive from these photos. It is bright but the color shows as white because the photoelectric chips in the camera (CCD) are saturated from the luminosity. It could be white, but I'm not sure that this photo proves it. At any rate, we can't see the really hot parts of the WTC7 photo cause the camera angles aren't that good and the fire is much deeper into the building than the other.
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