The "Item Details" section available in the bill, expense and cheque transactions is to enter the details of the products or services that are purchased. These are the products or services which are also created/entered in QuickBooks (in the Products & Services section).

However, if the products or services that are being purchased have not be entered as product or service in QuickBooks (in the Products & Services section) we use the "Account Details" section to enter that information.

For example, if the user purchases "Product1" from his supplier and he has created "Product1" in the Products & Services section of QuickBooks, while entering bill he will use the "Item Details" section to enter the details of the product. The account associated with this product will get debited in this transaction.

If the user is entering a bill transaction for "Rent" which is not available as product or service in the "Products & Services" in QuickBooks, while entering bill he will use the "Account Details" section to enter the account e.g. "Rent". When the transaction is saved the account entered here will be debited.

The other use case could be where in a supplier bill we have some line items of charges along with the products & services. In that case the products can be entered in the Item Details section and charges can be entered in the Account Details section.