The multicontroller allows sequential mode- basically, pump 1, 2, 3, 4 and then 1, 2, 3, 4- you need 4-8 pumps to use this.  Tide mode, one pump on, one pump off.  2-8 pumps can run this program.  Pulse mode, 1-7 seconds switching between two settings.  Their are two seperate settings for two channels, with branch adapters, up to 4 pumps per channel.  The single controller only runse with pulse mode and the photo cell is an accessory.