Dreadnaughts generally feel "looser" in terms of sound, but at the cost of a certain "muddiness" on individual strings. It's a more bluesy sound too.

"Folk size" (which doesn't seem to have a proper name - "jumbo" is sometimes used, but strictly that relates to the overall size of guitar as well) as Richard says generally gives a more "focussed" sound which is better for fingerpicking. There's a reason that classical guitars are shaped like this instead of like dreadnaughts.

The other factor is the size of it. Whilst there's the different outlines, they come in larger or smaller versions, and with thicker or thinner bodies. The larger the "box" of the guitar, the louder it is, but at the cost of maybe being less comfortable for your body and arms, as Midchuck says.

Do you play at all right now, or are you really starting from scratch? If you're a complete raw beginner, maybe getting a cheap classical for learning on would be a good move. Classical (nylon) strings are generally easier on the fingers than heavier steel strings - it is possible to use ultra-light electric-type strings to reduce the tension, but then you tend to lose the "feel" of the instrument. (Before you ask - sadly it isn't possible to string most steel-string guitars with nylon strings, due to the design of bridge that most steel-string guitars have.) A cheap classical should be cheaper than a steel-string, especially if you can find one second-hand. And then you can go and get a steel-string when you're good enough to be able to play it and hear whether it sounds like what you want.

Before you worry about this, worry about getting a guitar with a solid top. There do exist guitars with plywood tops that sound good (I was lucky enough to pick one when I went shopping for my first guitar :-) but it's unusual - usually they're cheap crap. A guitar with a solid wood top is almost guaranteed to sound better than a plywood top, whatever shape or size it is.

Graham.