The main difference is ease of installation. From their site:
"Installation requires cutting and crimping of the factory cables, as well as drilling 7 holes in the factory battery mount. You will need access to a heavy duty cable crimper to complete this installation"
Our kit does not require you to cut your factory wiring or any special tools for installation. Also, our tray and lid are far more substantial than theirs, and comes in a very high quality powder coat. Our system also includes busbars for easy connection to accessories, while their's does not.