Hello Jason welcome to the Blade Forums.
If I had to state the biggest differences between these two it would be that the Carbon V knife is made of high carbon steel, manufactured in the US, and has a factory V ground edge or cantled edge setup.
The SMIII knife is made currently in Japan, is a laminated stainless steel and the edge is hand convexed.
The steel difference makes sharpening and overall maintenance a bit different as well. The carbon steel tends to sharpen a bit easier, but will accumulate rust much faster if neglected. Either knife is a good choice.
Thanks to everyone for your comments.