Stock Trading and Other Things

What is the difference between billing systems and PayPal?

What is the difference between billing systems and PayPal? Billing systems such as Verotel and CCBill are offered seperatly to PayPal on many sites and offer instant credit card payment, but isn't that what PayPal does too? Does PayPal require membership? Is more than one solution neccesary? What are the commisuion rates, monthly charges etc? None of the magitude of web sites I have found answers these questions.
Thanks.

Public Comments

1. depends what your saying about billing systems see you have the site lets say ebay they ask for a credit card number but your not sure if you trust them many sites offer paypal were that site only ask your account number and pay pal will pay themas instead yo giving all your info pay pal just gives them your money