They are both K-frames chambered in .357 Magnum.

Besides the sights and the material, a Model 65 does not have a shrouded ejector rod or serrations on the grip frame. It has a heavy barrel and the Model 65 shipped with service Magna stocks while the (square butt) Combat Magnum had target sotcks.

A 65 is an M&P like the 10, 13, and 64.