Authorize.net is mainly a payment gateway. While it will allow you to do very simple recurring payments it will not give you the robust subscription and customer management features of an actual recurring billing system like Chargify.

For example, Chargify::

• Can prorate your customers if they change plans mid-cycle.
• Has a dunning management process that will automatically reach out to your customers when their credit card payments fail.
• Can process coupon codes and discounts. Great for companies using referral programs.
• Allows you to track units consumed by your customers (metered billing) and then bill them accordingly (think of minutes used or sales leads purchased).
• Allowing you to track "seats" used by customers, such as billing your customer based on the number of software licenses ("seats") they use over time.