As far as I know the yellow tops are more for supporting a system, they are a deep cycle battery and the red top is more of a starting battery, the red tops have more CCA's (IIRC) to aid in the process of starting the vehicle. You can go
here to learn about the yellow tops and go
here to see info on the red tops, the links take you to Optima's Website. Im sure others will join in with a deeper reasoning on both batteries.