One of the more popular layers in Google Earth, and one of the few that I rarely turn off, is the [Roads] layer. This layer simply overlays road lines and names on top of the imagery in Google Earth, and can be quite valuable to use.
This is similar to the “satellite” view in Google Maps, though Google Earth makes it much easier to add additional layers of information to your view, as well as dive into 3D as needed.
However, Google Maps also has the simple “map” mode, with no imagery showing, which Google Earth doesn’t offer — there is simply no way to turn off the base imagery. However, if you put a full-color overlay on the earth (such as some of these), it has the visual effect of disabling the imagery and giving it a clean road map feel.
To turn the roads layer on or off, simply click the checkbox next to [Roads] in the main “Layers” section of Google Earth on the left side of the screen.