Facebook for employees only (internal)?

[BlameMe]

My company has a Facebook fan page and we are wanting to start a Facebook page for employees only to share updates, catering menus, contest, activities and so forth which should we use. Facebook fan page or Facebook group page?

Here are the major concerns:
Allowing the public to see what we post
Connecting HR (my role) to employees via Facebook
Having non-employees having access to the page

Which do you think is best for an internal Facebook page, and why?

[I Try 2 Spy]

Facebook explains:

Pages allow real organizations, businesses, celebrities and brands to communicate broadly with people who like them. Pages may only be created and managed by official representatives.

Groups provide a closed space for small groups of people to communicate about shared interests. Groups can be created by anyone. is just that.