Honestly I have no idea, I've never owned one before. I just picked that one because it had a bigger display which leads me to think it I can display more info and perhaps more functions.
My understanding of these things (which may or may not be accurate) is that they scan the ECU of your car for any error codes (which most likely trip the check engine light on your dash) and maybe some other fuctions. Not sure if they simply give the numeric error code or if there is an explanation of what the codes mean.