Hi

Like you I too do not have an X5 but it's a BMW all the same. Mine is an E65 730d SE

However, I understand the main diference is the ability to display actual pictures of MAPS and show the direction of travel/due north and perspective. High will do this whereas the others will only show pointers showing direction to travel/trun in with corresponding voice commands - Ve Haf Vays off making you obey!