The only difference between e-commerce and conventional commerce is that goods in e-commerce are purchased over the internet using a credit card. Also buying and selling can be done during 24\7, not like the conventional commerce that is related to the weekly holidays or closing times.
Most e-commerce websites consists of two sections, the public and the admin side. The public side is what appears to the customers and where they can see and buy the products. The admin side can only be seen and accessed by the merchant, where he can check the orders, add and remove products, change prices, change themes ...etc. and the admin has to enter a username and password to access his account.