A - A conventional 3 way speaker with dome tweeter and 6" mid - 93 dB sensitivity on the top section, with a pair of 8" or 10" woofers (active). A fairly slim speaker with plenty of bass extension.
B - 8" passive 2 way with compression driver, 8" waveguide and 93 dB sensitivity. More chunky with just enough extension to mate with a sub (80 Hz). Higher output than A and a more controlled dispersion pattern.
C-10" floorstander with about an extra octave bass extension over B. 94 dB sensitivity.
D - Satellite version of C, similar to B but with more output.
E - Highest output and sensitivity of all options, basically a larger version of D.
F - Second highest output of all options, cheaper than E but more chunky in appearance due to 12" driver and waveguide. Technically better waveguide but more "pro audio" in appearance.