The Kadee facsmile is newer. Apparently the paten on the 805 style Kadees ran out, so a number of copies have started. Kadee meanwhile started a 7xx series that has 4 different shanks for over, under, normal, or long. They are compatible, but tighter than the 805s.
I notice that the knockoff atlas couplers while looking identical don't seem to work as well. I replace the Atlas springs for both center and knuckle with softer Kadee springs which can be bought separately. The atlas version does not seem to swing as smoothly in the box to me.
