This allows an automatic withdrawal annually through Paypal so you don't have to manually pay each year. You can turn off the subscription in Paypal account anytime.
One Time Payment
This is a one time payment for an annual membership. You can pay with a credit card without a Paypal Account(On Paypal page, scroll down and select Pay with Debit or Credit Card) You can still pay with Paypal Account if that is your preference.