The biggest difference? You might have problems sending in-game gifts to friends. However, it's not a problem at all, rather the result of Facebook setting limits on how many people you can send gifts to per game, plus an overall limit on gifting per day.
A Zynga rep had this to say about the changes, "Unfortunately since we do not control these changes we cannot provide "exact" details as there is no exact science as to how many requests you will be able to send on a per game/per day basis."
Of course, considering the millions of people who play these games (and send gifts), we're sure all of that activity taxes Facebook's backend resources, so we can understand why the social network decided to lay down the law.