Key PointsMost of Costco Wholesale's growth comes from its memberships, not its retail sales.Walmart has done an impressive job of expanding beyond traditional brick-and-mortar retail into areas such as advertising and e-commerce.Costco's stock is currently more expensive than Walmart's.10 stocks we like better than Walmart › There are countless retail businesses, but only a few can match the scale of Walmart (NASDAQ: WMT) and Costco Wholesale (…