Organic Valley's Pasture Butter, I know that the difference must be in the grass. Organic Valley's Pasture Butter is made from the milk of cows who have been grazing summer pasture. Regular store butter comes from the pasteurized milk of cows who are kept in confinement and fed grain (yes, even the organic butter). Yuck.
Organic Valley's Pasture Butter is pasteurized also, but the color, the flavor, and the texture are the same as the raw butter I make. I'm guessing that the raw butter is still better nutritionally because it has all the enzymes and vitamins that are destroyed in pasteurization. I'm not sure though because Organic Valley's Pasture Butter is cultured, but I think the culturing is simply to ripen the cream for better flavor, which I do by letting it sit out at room temperature for a while. I do know the Pasture Butter is better nutritionally than the regular store butter because it has all the CLA (conjugated linoleic acid) from the grass. The Nourishing Gourmet has an excellent post on butter from grass fed cows that includes an explanation of its nutritional benefits. It also gives the low-down on Kerrygold butter from Ireland. It comes from grass fed cows as well. If I couldn't get Organic Valley I would definitely buy Kerrygold. I am getting the Organic Valley for approximately $3.68 per half pound. I have bought it at Kroger, HEB, and Whole Foods. I have a bunch stashed in my freezer because it is by nature a limited edition product.