What's the difference between customer, account, and site at the Business Level?

Transactions set at the customer level to view or modify, encompasses all of the transaction activity associated with the customer. For example, a dunning letter at the customer level is inclusive of transactions at the customer and account level.

Transactions set at the account level to view or modify, are for a particular account and include transactions for all the bill to sites in that account.

Transactions set at the site level to view or modify, are specific to the bill-to location.