Isn't inflammable and flammable the same thing? Or do I not understand my own language.
Yes, but most authorities are trying to phase out inflammable for use, due to the possibility of misunderstandings. Since the prefix 'in' means 'not' in almost all words but this one, it just causes confusion. Some people use inflammable for stuff that is highly combustible, that catches fire readily, more than just flammable, but that's not in general usage.