Overeem will stuff Cain takedown attempts alot easier than JDS. Overeem will back Cain up against the cage and knee him or he could likely get the clinch and then come the knees and punches.
Overeem has better wrestling and grappling than JDS that is for sure. Overeem has alot more tools to beat Cain with while JDS only had one way and that is big power punch.
Also, Overeem has more muscles, therefore gas out faster than JDS.