Web sites that have integrated Facebook’s new social plugins, especially its new Like button, appear to be benefiting — more users are coming from Facebook to their sites, for example. But we’re also hearing mixed messages from some Page owners about the benefits of Facebook’s recent changes, including lower growth in their fan counts. Some developers say they’re seeing the same things.

There may be some confusion among users about the new interfaces, and the meaning of the term “Like.” Facebook tells us it is tweaking the products to improve results.

First, a quick review of the relevant changes and launches. The company originally used the term “like” as a simple feature in its news feeds (which it borrowed from FriendFeed). If your friend posts a funny status update, for example, you can click on the “Like” button. Doing so shows your name beneath the status update, along with a thumbs-up. The action also generates a story about it that appears in your personal profile feed, and in your friends’ news feeds.

The company has expanded the Like concept in a couple ways within the last several weeks.

One is that it has changed the terminology around its fan Pages from “Become a fan” to “Like.” So if you find a Page for a new music group and you want to become a fan, you click “Like” at the top. This means you’ll show up as a fan on that Page and in your personal profile, and a story about the action will appear on you personal profile feed and in your friends’ news feeds.

Facebook also recently required all users to alter how they provide information in their personal profiles. It asked them to list Pages in their personal profiles in place of their existing information. So if you previously listed your hometown, the education institutes you’ve attended, your favorite food, music, movies, etc. you either had to match these items with Pages or you had to delete them.

Then, Facebook launched the Like Box button for other web sites. The button, and the other social plugins, have appeared across more than 50,000 web sites since the product launched two weeks ago. You’ve probably seen them on your news sites of choice. If you click on the Like button on a news article, you’ll generate a story about this in your personal profile and in your friends’ news feeds. (Note: companies can also alter the Like button to have it work the other way, so that when you click the Like button on another web site, you become a fan of its Page. However, it is not clear if this practice is widespread enough to have an impact at this point.)

In sum, Like now means users are either just sending out a lightweight message to their friends, or also becoming a fan of a Page. The difference between the two is not always obvious to users, so they may find themselves unintentionally becoming fans of Pages when they just mean to share the information with their friends, for example. The transition of personal profile information to Pages also appears to have confused users about their relationships to Pages.

The combination of all of these changes may be causing some users to first check to see what Pages they are listed as being fans of within their profiles, then going to those Pages and un-Liking them. This would explain the fan drops that some Page owners are reporting — although the only data we have to support this is anecdotal descriptions from users and Page owners.

Facebook says that is continuing to test and refine the Like Box plugin. At first, the company showed the Like button with a solid blue background if the user had already clicked on it. It changed this on Monday, so now you’ll see “You Like This” if you’ve clicked on the Like button — unless you click the button to become a fan of a Page, in which case the button will disappear. If you want to un-Like your Like in the Like Box, click on the button again. If you want to un-Like a Page, you scroll to the bottom of the left-hand navigation column and click “Unlike.”