The only real difference that I know of is that the mix has no soil in it. It is a soiless mix that contains peat moss, perhaps some ground pine bark mulch, and maybe some perlite. It is very light and fluffy. The other, has actual potting soil in it, and if it comes from Miracle Gro, it may contain some sort of fertilizer. When I plant my roses in pots, I never use the potting soil, because I like to add my own fertilizers as needed, without help from the ten cent seats. I generally plant in Fafard #2, a soiless mix.