Both Insomniate and Insomniate Simple are lightweight apps that run in the background (System Tray area). The main difference between the two is with the Simple version, there is no GUI. You just launch the app and forget about it. As long as the app is running (In the System Tray area), the computer will not go into Sleep/Standby mode. With the 'non' simple version, there is a GUI where you can manipulate Insomniate's built-in countdown timer and change how often you want it to interact with your computer to keep it awake.