I know of at least a couple of different sizes. One like mine and a cone in that is embossed Farleys.
Jeff, (Kungfufighter), would probably have a better idea of how many different sizes they come in.
Supposedly there is a quart size, but I've never seen one.
The Farley's come in 3 standard sizes. The small one is the most common. The middle and large sizes are rare, and the middle has typically been the toughest to acquire. There are some variations in the small size, one with squared shoulders and one with more rounded shoulders.
You can see some variations in color, however the green is very rare.
There are also labeled umbrellas, igloos, pints and quarts. I ahve spoken to someone who claims to have seen the mythical embossed quart, but I'm not sure if it exists... time will tell!