Propane is a flammable gas which is non-toxic and colourless. It is intentionally odourised with a special chemical agent (easy to detect a leak). Propane possess a high thermal capacity with clean burning properties.
Nitrogen is a non-flammable gas which does not support combustion. It is colourless, odourless and non-toxic; it is almost a totally inert. IG, HP, UHP Nitrogen is produced with a food grade classification.