I'm not sure what all of the differences are, but comparing the images and specs for the Droptine and the FF II 4.5-14x42 there are only a couple of differences that are readily evident.
- The FF II has metal caps and metal Objective and Mag rings vs. apparently plastic ones on the Droptine.
- The Droptine is available with the Ballistic-Plex (an excellent reticle, IME) or a mil-dot reticle, whereas the FF II comes only with the Ballistic-Plex.
I do not know how the Droptine would compare to the FF II in terms of optics, but I have very carefully (systematically, using the USAF optical resolution target) compared my FF II to my Vortex Viper 6.5-20x44, Sightron SII 6-24x42, Sightron SII 3-9x42, Redfield Revolution 3-9x40, and a few other scopes that I have. At any given magnification, the FF II is slightly better than the Vortex or the Sightron 6-24x, and significantly better than the rest. I subsequently went out and bought 3 more of the Burris scopes for some other guns. If 4.5-14 mag range suits your needs, I HIGHLY recommend that Burris.