Well Catlin, because you can view your model all at the same time from different angles in virtual space using the 4 views, you can better manipulate the shaping of your model to suit your needs. There are just too many terms and to discuss them individually would fill volumes and hardly a topic to which justice would be done on a forum thread. In these modeling programs you can model using solids which are often called primitives and using boolean techniques (named after the person who first came up with the algorithm for the technique) you can create fairly basic models just like you can in Bryce but these are real booleans which like AS said leave only the positive forms reducing the chaos on screen that you get in Bryce and lowering the amount of polygons making up the model making for a lighter model. You have many different techniques at your disposal with which to create your models. Way too many to go through here but you have techniques like lofting, which is much like extruding, where you first create a silhouette shape of the object using lines, often are called bezier curves (lines) which have control points (vertices) along it and by pulling and pushing on these control points you can shape your line into any shape you want. Then this shape can be lofted or extruded (both terms are often used interchangeably) along another line, which acts as a rail (axis) whose length dictates the depth, which your finished solid will be when the line shape is extruded along it. Another popular modeling technique is NURBS (Non Uniformed Rational B-Splines), which is actually a compilation of different model surfacing techniques. Generally, you first create a front view and a side view of your shape or perhaps an axis line (rail) depending on which surfacing technique youll be utilizing using spline curves (similar to the bezier lines from above) creating a mesh frame. Then you select whichever surfacing technique is best suited to put the skin on your mesh frame thus creating the general form of your model. You can then push and pull on the individual control points to better define your model, say a head model for instance. Once youve finished detailing your model, it can be converted into a polygon mesh and at this point you can start texturing your model and exporting it to other programs. NURBS allows for more organic models by allowing the user more control over fine detail. Metaballs can used to better represent certain organics. Would be nice to get a program that would allow vertex push/pulling on a metaball wireframe. Each modeling program handles these techniques differently and is what makes one more popular over another depending on what the end user finds easier for him/her. Hope this helps explain and de-mystify some of the more often used terminology a little.