You will probably get a better answer to a technical question if you ask it at the >>Google Earth Help Forum<< (link also at the top of this page). Your question, however, is an interesting one. The imagery (both default and historical) should be identical for both Google Earth and Google Earth Pro, and for all available versions. The 3D Buildings Layer, however, probably has a differently dated imagery, so it may be a matter of whether or not that layer is enabled. Please provide us (or the Help Forum guys and gals) some placemarks on areas where you and your friends are seeing different imagery.