Credit cards are a very useful and somehow addictive medium of expenditure as they allow people to carry very little amount of cash when they go shopping or travelling to any outside area. Their are variety of these cards available through many banks and financial institutions but the bank name or its reliability does not matter(it only makes the interest rates on your credit differ), the basic differences are the brand(VISA, MASTERCARD, AMERICAN EXPRESS, DINER etc.) out of which the first two are preferred if you are in Asia since they are accepted at more locations instead of cash.
The second differences come in the credit limit and the amount that you can encash in need of emergency from a designated bank. That difference is shown in the color of the card(usually silver and Gold) with Gold being the higher standard.
The use of credit cards also facilitates the purchases and membership fees being payed on the internet, but that would be a lengthy debate on its own.
I hope this helps you.