I am a paid member, but I keep seeing the word enrollment.  What is the difference between an enrollment and a subscription?

Good question!  In a nutshell, they are the same thing.  Paid memberships used to be called "subscriptions," but now they are called "enrollments."  Subscribers are now called "enrolled members" (and unpaid members are now called "registered users.")  Paid members pay the same price and receive the same benefits as before; all that has changed is the wording we use. 

We found it necessary to make this change to accommodate a new and useful feature called Content Subscriptions.  You might notice the word "Subscribe" shown as a link in blog posts and forum threads.  If you click on this link, it gives you a number of options to choose from.  Subscribing to content in this way will result in your receiving e-mail notification when various additions or changes are made in that thread, by that author, or in other ways, according to the options you choose.  To manage your content subscriptions and preferences, click on "My Account" in the navigation bar and choose "My Content Subscriptions."