What is the diff. Jumbo size and normal acoustic guitar?

Simply put the larger sizes of guitar are louder. If you play a packed folk club with a dreadnought you'll be heard at the back. Resonator guitars are louder without being bigger but they are expensive.

Most beginners find the physical size of a jumbo off-putting. When in the guitar shop make sure you sit down with the guitar and can find a good strumming position where your arm sits nicely atop. Even in standard size small differences in body depth and sound hole position can make the difference between something you'll never be comfortable with and 'your guitar'.

Alot of beginners favour semi-acoustics because they have less 'back' and are easier held. Of course with these if you want to be louder you can buy an acoustics amplifier.

Blast from the past again.

This is a very good question that begs you to try the guitar before you buy it.  I own two jumbos.  One is a Gibson and the other is a Guild.  Both of their bodies are about the same size and shape.  The Gibson is made of Spruce top and Maple sides and back.  The Guild is a spruce top with rosewood sides and back.  Both have mahogany necks. The playing volumes of the two guitars are very similar but the Gibson has much more bass.  Not a little bass.  A LOT OF BASS.  The Guild has very balanced volume across all the strings but the Gibson gives me an opportunity to accompany myself.  If I play/ pick the bass line while I'm fingering other notes it almost sounds like two guitars.  At first I didn't like the "imbalance". Now, I love it.   But to get to the meat of the original 2007 question, "What is so special about a jumbo acoustic vs. a normal acoustic"... Answer is: Nothing and everything.  Example:  Over all, my Ovation sounds better and is louder than the Guild or the Gibson (to me).  The Ovation is a very small body by comparison.  The Gibson is so large that I don't think a small person should even try it.  Volume and tone of any guitar are very subjective.  Loud is not an issue in this day and age of electronics and amplification.  Sound quality, comfort, tone, and playability are the issues (Ok, looks are important too).  I have discovered that no matter how much I love the Gibson,  I can't sit down with it in a chair and play it comfortably.  I can hang out all day in a lazy-boy with my Ovation.  I don't know if age has anything to do with this but as I get older, I'm looking more at the smaller body guitars like the Gibson L-00 or Martin's OOO series.  Long story short: Bigger isn't always better. But, sometimes it is.

Is it correct to say that a jumbo is more of a strummer guitar vs fingerpicking and flat picking on a smaller dread or concert body guitar?