What is the difference between Paypal IPN and Paypal Express Checkout payment module. How should i know that which module is best for me. Recently Paypal give authorize me thorugh my email address.

In Paypal IPN module i give this email address and on my store (through paypal verified) verify , it is working Paypal verified site.

I don't know about my paypal account. how could i know it?

Now can i used Paypal Express checkout for customers payments?