Mandophil(e)-The differences are in in both the arching, graduations and finish thickness. #There are the obvious cosmetics of tuner styles, inlay and such, but the late Ferns have thicker tops and backs along with thicker shiney lacquer finishes for a heavier overall feel and sound. #The early Ferns differ from Loars in arching, but the graduations are very good and the finish is thin for simply a different and brighter sound than a Loar. #Cosmetically, the early Ferns have gold plated hardware that is identical to the silver Loar hardware.
Again, direct comparisons can be made with the modern F5's mentioned above.