Old vs. new.
The older Porta-Botes had canoe bows and sterns. The newer (not sure when they made the switch) have a flat stern that can more easily accommodate an engine.BTW, I like my 10'6" Porta-Bote. It's easy to put together and take apart, it's virtually indistructable, can fit three adults, can easily be rowed, planes easily with my 4HP engine (even when loaded down), and stores nicely on deck strapped to the life lines.~ Happy trails and sails to you ~ _/) ~