my interpretation of heirloom quilts (or quilting) is that it obviously has a lot of the creator in it, really tok time to do a good job and I think a lot of quilting, maybe different designs and such.
And just in case any of my children/grandchildren read this: ALL OF MY QUILTS ARE HEIRLOOM! AND DON'T FORGET IT!
they'll probably never be in a museum but I certainly put a lot of ME into them!