Both LinkedIn and Facebook are excellent social media platforms but both have their independent individual characteristics.
1. LinkedIn is highly focused on professional networking. It is a heaven for recruiters as they can gauge the credentials of the potential employees and also contact prospective recruiters with the help of their existing network.
Facebook is more casual and diverse in nature and really encourages interaction amongst its members. As they opened their API for application developers, many interesting applications including games, polling apps, etc. intrigued and captured the imagination (and time) of the community members of the platform.
2. Linked in has the subscription based revenue model and also has ad based revenue stream. Facebook on the other hand has ad based revenue model as of now. But they are also collaborating with mobile companies like Nokia for OEM deals and must be making big bucks.
3. In Facebook one can upload pictures / videos to share with friends …. Linked in has stayed away from rich media game play. Profile pictures are allowed but in all probability one would find people in their business suits at linkedin. In Facebook one can be more relaxed and opt for more casual profile pictures as they are out there to socialiaze with friends and have fun.
4. LinkedIn has added the Q & A module for knowledge sharing. Facebook does not have such a a mandate.
5. Facebook allows building web pages to promote products or service or organization or event. Linked allows the users to add companies which can show in the search results.
In a nut shell, LinkedIn is a more focused social media platform. Facebook is a larger giant allowing people to be more casual and encouraging them to indulge on the wall!