14. A major difference between the Periodic and Perpetual Inventory methods is: El. b. We have to use two journal entries when we record sales, sales returned and customer collections under the Periodic method. We use General Ledger Accounts such as lCost of Goods Sold, Purchases, Purchase Returns, Purchase Discounts and under the Periodic method. We use the Merchandise Inventory account when we record the purchasing of inventory under the Periodic method. We must calculate Cost of Goods Sold at year end under the Periodic method