thanks for that clarification. I assume I use one or the other right? Would never need both?
Check valves are devices that allow water to only flow in one direction. If you don't want the irrigation pipes to drain out the lowest spray head when the system is turned off, you install check valves under each and every spray head.
Electric valves are simple On/Off valves that allow you to start/stop the irrigation system using an electronic controller. If you plan on having someone manually turn the water on/off, you don't need electric valves. If you want to be able to set the system to automatically turn on, you'll want electric valves.