If I "share" via e-mail, then I transmit a document to others. After this, each recipient has a separate copy which, thereafter, is completely out of my control.
If I "share" via social network, then I upload a document. This makes a single copy, accessible to previously chosen people. It is (depending on the social network) somewhat under my control. Others can comment on it.
If I "share" via something like Dropbox, then I make the document accessible to others. No copy is made. If I share via URL, then I give read access. If I make a shared folder, then I give both read and write access.
Now, we techies know these are different things. Our mental model of non-technical users' thinking might suggest that, to them, these are all the same kind of action.
But are they?
Does an average non-technical user think of folder sharing, Facebook posts, and e-mail messages as the same category of action? I'm not sure he does.