On the other hand, the process of machine quilting lays a continuous line of thread on the fabric
In addition to differences in the effect of the stitched line, some designs are simply easier to accomplish with one method than the other.
For hand quilters, starts and stops are easy. Starts and stops are more problematic on the machine and must be carefully handled. For this reason, machine quilters will want to reduce the number of starts and stops by designing long lines of continuous stitching.
For machine quilters, tiny circles and twists and turns are quickly and easily accomplished using free motion. A hand quilter working with a hoop or a frame either will have to turn hoop or body continuously or learn to quilt wrong-handed and backwards to execute these same designs. The hand quilter will find it easier to design quilting with gentle curves and less frequent changes of direction.
In sum, both hand and machine quilting have their characteristic looks and limitations. As designers of the quilting, we can learn to use these characteristics to our advantage.