Andrea my take is as follows:
There are some obvious differences - Autoroute and Mappoint are on your computer, Live Earth is web access

...but the important ones for usage are
1) Autoroute is not programmable
2) Mappoint is programmable and supports territories and data mapping
3) Live Earth has much wider route calculation range; Autoroute & Mappoint only cover (either) North America or Europe and in Europe coverage of gets worse as you move East. Live Earth allows route calculation in (for instance) Russia, Turkey, China and former Yugoslavia. Incidentally be warned: distances are OK for these places in Live Earth but journey times (based on 50mph average) are unrealistic. Also, all routes are road routes where, say, in Russia trains are the lead transport mode.
Also Live Earth is much better than Google Earth for these journey calcs.