I'd imagine that it does look perceptibly different. After all, humans do not, generally, burn on their own accord. The human body contains quite a lot of water, which has to evaporate before the dry matter can burn. Even fatal burns usually don't strip away much more than the skin - so if your arm is burned through to the bone, Somebody Did It Deliberately. Whether it's possible to tell the difference between napalm and phosphorous, I'll leave to the forensics people, but it's for damn certain that you didn't have an accident with a jug of kerosene. Or even concentrated sulfuric acid.

- Jake

Friends come and go. Enemies accumulate.

The point may be that the use of these kinds of bombs are prohibited by international law, especially when you are intentionally bombing civilian targets.