Well the 8th ingredient in the "Pro" (?) Series is Tallow Acid or Palmitic Acid. In the "Expert" line it is Sodium Tallowate. Maybe someone much smarter than I am could mention what the difference is . The 12th and 13th ingredients are flipped between the two. Fragrance and Sodium Chloride From 14 on there seems to be quite a bit of difference. It has gotten my interest though. I will be purchasing the other type and comparing them just for the heck of it. Does the one you have say to use with a brush ? I wonder if there is a "Expert", "Pro" and "Plus"(+) series? That would really make this interesting.