If we use something every day, we should know how to do, and understand that means everything we do and that brings consequences. Facebook each day is bigger and covers more areas become more complex, and that growth may not seem to find the balance between expansion and ease of use. So, most of us use Facebook and perform actions on it do not always know what the consequences are, or at least not too light. So I will try to clarify some of these differences and what they entail.
On Facebook you can make two types of actions, you do within the social network, or you do outside of it: On websites including Facebook widgets, or even mobile applications including its SDK.
In turn, these actions can be performed on social network elements, and elements external to the social network, which are not created and reflected on it, what they call the Open Graph, which is anything in the world without being on Facebook, they can store and process classified as an element, thanks to its protocol OGP, Juan Merodio explains it very well.
And this combination produces different results depending on the action by combining perform each of the foregoing. I try to explain:
Like, is an action that tells others about something our preferences.
But if that Like, you do it on a Facebook fan page, you will see your face on the Facebook page as a fan, as well as on your wall, but not as part of the news feed, but in the square on the right of Recent activity, and in the home of friends.
If same Like, what you click on an item in a blog anyone has the plugin installed and that is part of the actions that Facebook can do outside, its impact will be negligible.
If Like what you do to a website that has the plugin Likes with the faces of the fans, is because this website / blog has created his Facebook fan page, so Like that it will be widely highlighted in the home of friends, as an action of yours, especially with recent changes that draws all the header of the page under your Like.
This action every day seems more interesting, especially if we have important and really stand out on Facebook.
If the Share you do, both from a story of Facebook, that is from a publication by one of your friends or fan pages, groups, etc. or from an external blog, in the end becomes a new publication yours in your news feed, so acquires such importance as a publication that is one of the most prominent, as discussed below, so if you want to highlight something an article , use Share rather than Like.
This is the preferred action for Facebook, which you make from the Home, to say something to else, but not a content based on a photo, or a foreign publication, but always contributing their own content or uploaded by you, either text , image or video, or whatever.
And so is the action that Facebook will give more power and importance, indicating that write directly on Facebook, as you would on Twitter, for example, still is not the most used. At least I almost did not use, and I usually always post from an article or a similar share.
This action is very similar to Post and has consequences provided it is done in a story within the social network, if you comment in a blog that uses the Facebook comments, we will be talking about the Open Graph and its importance is really insignificant, not appear prominently in almost anywhere.
In the end, what Facebook stands giving more importance are the actions that take place in the Open Graph, but proper elements created on Facebook, saying it indirectly, and even becoming almost blackmail, as when Google we want to force us to use Google+ to improve our positions on SERPS, that if those responsible for websites use more of all of Facebook, we have a greater reward being more prominent, otherwise it will barely impact.
You see, the differences are significant enough as to not be aware of them, as we want to emphasize, or who want to extend our under something, or recognition of something, with our social actions.
Have I missed something? Would you like to add a point or action?