Most of the programs designed especially for quilters are vector drawing programs. Because we handle objects in our piecing and appliqu , and line in our quilting, the environment in a drawing program generally seems more familiar to quilters. You can make traditional quilt blocks very simply in Corel Draw, but you can also make free form designs. You can make any line or object, then change it's size, shape, and proportions and color infinitely. My quilt designs are usually a combination of objects that I have drawn directly in the computer and line drawings that I have drawn by hand on paper then scanned into the computer using a flat bed laser scanner.
Bitmaps are like microscopic postage stamp quilts.
They are a bunch of little rectangles called pixels that line up in rows and can look like a drawing or a picture. Individual pixels can be altered in a paint program, but I haven't done much with that. To convert the bitmap to a vector drawing, I use a little inexpensive program called Streamline. All it does is convert bitmaps to vector drawings, and it does it very well. I can then import the Streamline file into Corel Draw.