Pricing is based on intricacy of piecing as well as the intricacy of quilting.
Utility quilt means the quilt can be handled on a day to day basis.
Heirloom quilt means the quilt is to be looked at and not handled much.
Art quilt means they are too small to use as a vessel to keep warm, unless your walls are cold.
Simpler designs with simpler quilting are generally utility quilts. Quilts with a large number of pieces, large amounts of quilting, and much time to construct throughout the quilt building process are generally heirloom quilts.
However, I have a few in my collection that experimentation with patterns resulted in less the perfect results. They may look heirloom quality, but will be sold under the utility umbrella simply because there are design flaws within.