http://french.about.com/library/weekly/bl-conclusions.htm " Parce que Because Parce que is a subordinating conjunction and can begin a sentence. Parce que introduces a cause, explanation, or motive - it explains why something is done. Je ne suis pas venu parce que mon fils est malade. I didn't come because my son is sick. Parce qu'il n'a pas d'argent, il ne peut pas venir. Because he doesn't have any money, he can't come. Car Because, for Car is a coordinating conjunction, should not begin a sentence, and is mainly found in formal and written French. Car supports a judgment or indicates a reason. La réunion fut annulée car le président est malade. The meeting was canceled because the chairman is sick. David ne va pas venir, car il est à l'université. David isn't coming, for he is (away) at school. "

"Car" et ''parce que'' expriment la cause, on peut dire qu'il n'y a pas de différence entre les deux. Gravity.

http://www.ccdmd.qc.ca/correspo/Corr10-4/Car.html