Do you know the difference between a Facebook Fan page and a Facebook Group?

Facebook Action Fan Page Group
Indexed in Google Yes No
Add extra applications (i.e. Twitter) Yes No
Message all members Yes Yes
Promote with social ads Yes No
Host a discussion Yes Yes
Page and visitor stats Yes No
Create an event Yes Yes
Discussion wall / tab Yes Yes
Can suggest to friends Yes Yes
Create a username Yes No

N.B. it is worth noting that changes, updates and developments are continually happening on Facebook.

Generally, choosing between a Fan page and a Group depends upon the subject matter, whether its personal or for a client, make sure you know the objectives and research first.