Being a toothbrush is pretty much the only thing that they have in common because their designs are completely different. The Source handle is straight, not angled like the Original and SCUBA, and the Source handle is made from recycled materials like dollar bills, wood, and paper. The Source also uses Replacement Heads which are 50% smaller than the Original/SCUBA heads. The Source can be either right or left handed depending on how you put the Replacement Head into the handle. The Original and SCUBA come in right and left hand versions.