number of models
Sometimes this is done to satisfy different market segments, for example, if someone has all hard wood floors, there would be no need for a power nozzle if purchasing a canister vacuum. On the other hand, for carpet, in most cases, you would want a spinning brush, so a power nozzle canister would make sense. Even then, that's only two models. One company that has lots and lots of models, at least in their canister line up is Miele. I think there are 15 or more models. I do think this can be confusing, although once you look at their models, there is some method to the madness. Miele has three canister series, C1, C2, and C3. The C1 classic is a full sized canister with basic features such as a knob for the speed control. The C2 compact series is a bit smaller, the down side to this series is that it takes smaller bags requiring the bag to be changed more often. The C3 complete series has the bells and whistles such as electronic speed control and a slightly longer cord. Once you decide which series you want, you can then choose the model in that series that includes the accessories you need. One thing I think manufacturers should do when it comes to canisters is, if you choose a model that does not include a power nozzle, it should still provide the ability to be upgraded later. As far as I know, the straight suction models from Miele, Sebo, and the straight suction version of the Riccar Prima and Simplicity wonder cannot be upgraded by simply purchasing the electric hose and power nozzle, if your requirements change, you would need to purchase an entirely new vacuum, or I guess you could use the Volt power nozzle, but still, if a company makes both a straight suction and power nozzle model, the straight suction model should always contain the circuitry to be upgraded to an electric hose.
Mike
