Both companies have ph balanced products; however Cosmetic Skin Solutions ph appears to be slightly lower than SkinCeuticals.
SkinCeuticals does use a slightly higher concentration of L-ascorbic acid (20%) then Cosmetic Skin Solutions (15%), however, both products give great results when used for a long period of time. The lower concentration of L-ascorbic acid is actually a plus for those with more sensitive skin types due to the fact that high concentration of vitamic C can cause redness and sensitivities.
Why is there such a big price difference between the two companies?
SkinCeuticals was the first product line to come out, the company has spent hundreds of thousands, if not millions of dollars in studies and marketing their product line. Cosmetic Skin Solutions in the other hand, is promoting their product line as pretty much the "store brand" version of SkinCeuticals. When you compare the two product lines, ingredients are nearly identical except for a couple little changes.
The main reason I chose to carry Cosmetic Skin Solutions in my skincare clinic was due to the price. Cosmetic Skin Solution is simply more affordable for my clients, making is more accessible for purchase on a regular basis. Using great skincare products consistently is what is going to give you good results at home and the fact that this line is less expensive makes it much easier to make skincare a priority!