I tried the D3060040A.JCV 757,3MB LaneAssistFull D3191030A.JCV 449,1MB LaneAssistPortrait, and D3153040A.JCV 44,3MB LaneAssist on an obscure interchange and saw two images in each, the full was higher resolution than the mid size, but both were full size and the showed trees in the background. The D3153040A.JCV 44,3MB LaneAssist was actually better resolution of the road and lanes than the 449MB file, but it did not show (blurred out) the background trees, etc. It appears the smaller file has the same utility, but focuses on the lane features not the background. In another post for an earlier version NT2012 it was reported the associated small jcv showed approximately 5 of 8 interchange pictures in the San Francisco area. Don't know if this would be true for this example.....Since there is lots of SD card space and the files don't seem to slow the unit loading it seems logical to use the big file.