In contrast, LinkedIn is primarily used for the purpose of professional, not personal, connections. Though I have only been a member of the site for a brief time, as I have explored I have found LinkedIn to be driven by business and employment. It does ask a few personal questions, such as a user's interests, birthdate, and marital status (some advise to omit these personal items from your professional profile), but other than that it focuses on job experience, education, and expertise. Many of the items that make Facebook so popular, like photo sharing, timeline posting, and instant messaging, do not exist on LinkedIn.
While I could not imagine deactivating my Facebook account for the purpose of personal connections, there is a certain draw to the "separation of church and state" type atmosphere of LinkedIn that I believe can be very useful in the professional world.