Hi Moon.......As Bert said Dreadnoughts are larger sized with less waist...the classis Martin that most people think of like the D-28 (D meaning Dreadnought). There are several makers using different "codes" for sizing, but the most commonly used is the basic Martin system of (from small to large) O,OO,OM,OOO,OOOO(M),D,J(Jumbo). The numbers represent a difference in dimension of not only width at the upper bout, lower bout, and waist, but also depth and some variations in shape as well. You also consider neck scale and width when choosing another guitar. Since you're used to one, another may feel very different. Different sizes have different tonal qualities also and then it IS important to take your body into consideration. Does the guitar fit you? Sometimes people get used to a guitar that is not a great fit, but becomes so after "getting used to it." (I think of Emmylou Harris who almost always uses a Jumbo) Playing that B, you're unlikely to find that a dreadnought is comfortable.

Try before you buy. If you have played the same model that you're looking to buy sight unseen, at least you know something about the "general" characteristics of sound and fit, but it is always a risk to buy sight and heard unseen.

Spaw