Not sure about the fire-proof qualities of either - but the space blankets that I have used (the cheap $2 kind) have no where near the strenghth of a contractor bag. By the end of the first night my space blanket was severaly ripped. They seem to shred when I simply look at them. I now have one of the thicker "sportsmens" blankets - hopefully it will fare better. Takes up a LOT more room and weight, though. I still have the cheaper kind - but I'd only rely on them for a one night emergency situation - not as a source of warmth for an extended period.