[Since a bank offers the variety of services to the customer, the relationship between the bank and the customer changes according to the type of service rendered.This web page explains how the contractual relationship between the bank and customer changes as creditor and the debtor, Lessor and the Lessee, Principal and the agent, assigner and assignee etc.]
Basically, the relationship between banker and customer is contractual in nature. Banker accepts deposits of money from his customers for the purpose of lending and investment and repays it on demand as per the terms of the contract of deposit. In fact, deposit accepted by the bank is actually borrowing by the banks from the public. The general relationship between a depositor and the banker is, therefore, the debtor (Bank) and the creditor (Customer). The relationship between the banker and customer is directly opposite when the bank lends money to its customer. The bank becomes the creditor and the customer becomes the debtor. Since bank offers the variety of services to the customer, the relationship between the bank and the customer vary according to the type of service rendered. When a banker accepts items like securities or documents for Safe-Custody from the customer, the relation between the banker and customer is the Trustee (bank) and the beneficiary (customer). The banker is only a trustee to the items handed over to him for safe custody because banker cannot use the items deposited with him, whereas in deposit accounts, money deposited by the customer can be used by the banker for his business. In the case of collections of cheques, bills and other instruments for customers, the banker becomes the agent for collection and the customer for whom he collected such instrument is the principal. Similarly, when a customer hires a locker from the bank, the relation between the bank and the customer is lessor and lessee.
Transfer of Life Insurance Policy, National Saving Certificates, Supply bills etc, to the name of the bank for the purpose of borrowing are examples of assignment. The transferor of the security is called assigner and the transferee is called the assignee. The assignee must give a notice to the debtors so as to complete his title, otherwise, until debtor receives the notice of assignment, his dealing with the original creditor will be protected. On full payment of dues to the assignee, the assignor can get the security re-assigned in his name.