Key Points Walmart and Costco are the largest and 3rd largest retailers in the world Costco has a club membership system and offers selected bulk goods Walmart has a wider ranger of product lines and services a larger customer base 5 stocks we like better than Walmart Few companies are more synonymous with retail in the United States than Costco Wholesale Corp NASDAQ: COST and Walmart Inc. NYSE: WMT. While both retail giants have rewarded investors over the years, their business models and strategies differ ...