Major differences between Granite and Marble?

I had been in this stone line for 5 years, let me try conclude them in a short Word: 1. hardness: granite is more stronger, so, it is could ues for outside, but marle not. 2. color: both are have lots of colors, but marble have more funs in veins and colors 3.radiation: marble have no radiation, but a few granite have. For some kinds of granites, the more darker color, more heavier the radiation is. 4.stability:granite is better