There are many extra features to the RKE versus the RKL. The elite can handle 250 modules versus 4, 4 channel waver maker versus 2 channel, can mix 4 timers to one channel, 2 standby modes versus 1 and more. This is all I remember of the top of my head. Most people would do fine with just the RKL, but I like the RKE because you could use it on every tank in the house.