Debtors account and bills receivable account are theoretically same. Both are called as receivables. When we sold goods to debtors account is debited. If we receive a bill from that debtor, we open bills receivable account by closing that debtor account. Thus, bills receivable account is nothing but debtor account. If the bill is dishonored on the due date, we again debit the debtor account in our books. For information and accounting purpose, we use both debtor account and bills receivable account.