EOS 6D Specs
EOS 5D mark III
6D - $2099.00 - Body only
5D3 - $3599.00 - Body only
One neat thing that the 6D offers that the 5D does not is built in wireless.. The built-in Wi-Fi® transmitter allows you to wirelessly transfer your images to social networking sites through CANON iMAGE GATEWAY#, or upload virtually anywhere from your iOS or Android smartphone* with the free download of the EOS Remote app**. You can use your smartphone for remote camera control and operation (with the EOS Remote app), or even print your images on a Wi-Fi® compatible printer.
There are reason's the 5D3 price is considerably more than the 6D and you really should look at both bodies before making a decision on either one. The biggest thing that separates the 2 cameras is the Auto focus systems. The 6D incorporates an 11 point AF system, while the 5D3 uses the outstanding 1D X 61 point system from Canon's top of the line flagship body. I can tell you first hand that it works flawlessly! fast and accurate. Something to be looked at very closely when deciding between these 2 cameras...
The nice thing that Canon has down here is given buyers 2 different price points for those wanting a full frame DSLR... Which one is for you ultimately is your decision, but which ever you choose you can bet both will produce outstanding images...