Parafin Wax is brittle when it cools off, so it can be cracked while it's on the fabric, and when the fabric is dyed afterwards, ONLY the cracked areas will get dyed.
Bees Wax is soft & flexible when it cools off, so it will not crack and when the fabric is dyed afterwards, there will be a clear unbroken line or image on the fabric.
Every new layer of dye can be preserved the color it is by waxing it before adding another coat of dye. Again, only the areas waxed will be saved - all other areas of the fabric will be dyed if not waxed, and the color of the unwaxed areas will change with every new layer of dye added. This process can be done over & over from lighter to darker colors.
After the layering of wax & dye has been completed, I boil & wash the piece a few times to get out all the wax & excess dye. The end result should be a clean image on the fabric.