The difference between a joint and a blunt was that a joint is rolled using rolling papers and a blunt is a cigar that has had the tobacco removed and replaced with mari-jane
a joint is where 2 parts, lets say bones meet. a blunt is having a worn-down edge or point; not sharp. that is the difference.
The joint is smaller and generally in white rolling paper, and the blunt is bigger and rolled in a brown blunt wrap.