The best comparison can be found at the Garmin International web page. But here is my quick version. The yellow(Basic eTrex) has no base map, nor does it allow you to store maps from Garmins Map Source Software.
The Blue or better known as the Garmin Legends has a base map which covers the United States and Canada. This map includes main State and US highways, small towns and large cities. It has more limited coverage of Mexico. You can load 8MB of maps on the Legend. This is approximately 35 topo sheets. Within the area that you have loaded the mapping software you can also locate points of interest near your map cursor. You can also locate freeway exits, and nearby resturants, and service stations. Each one shares a number of screen options. I consider the Legend a good deal.
The difference on the ground side-by-side trying to find the same location. The yellow will show your direction to the waypoint on a otherwise blank screen. The blue will point to the waypoint but will also show you are crossing a freeway. If the blue is loaded with topo software it will also show you that there is a small lake in your path. Advantage blue. :wink:
