Breast Milk Supply & Production: Toddler, Sam's Club

Sam's Club or Costco???

I have been going to Costco forever which I love their products and especially their return policy, but now I live at the area that Sam's Club is closer than Costco... Mostly I heard that Sam's Club and Costco are pretty much the same... Now My questions to all the fellow moms that what do you think of each of them, which one do you like and what do you like about them??? Thanks for the help. ^_^