There are three different types of Facebook accounts: Facebook Pages or Profiles, Facebook Groups, and Facebook Fan Pages. In order to create a Group or Fan Page you have to have a Facebook Page with a personal profile first. Each of these offers different networking and marketing opportunities.
Traditional Facebook pages are used to promote an individual or business while Facebook Groups are used to promote a common interest. Facebook Pages provide the strongest marketing vehicle of the three as they can provide marketers with embedded widgets that promote their pages externally.
The most important distinction between the three is as follows:
Profiles add each other as Friends, members “Join” Groups, and members “Like” fan pages.
Fan pages have the lowest level of active participation. You don’t join to participate you “like” the big advantage of a Fan page is that it is not private anyone can see it and it’s visible within fan profiles.
Secret: Only members see the group, who’s in it, and what members post.
Closed: Anyone can see the group and who’s in it. Only members see posts.
Open (Public): Anyone can see the group, who’s in it, and what members post.
Public or Open groups are crawled by search engines, and most importantly Public Groups can send out Facebook messages and events with email alerts. This is a relatively high profile way to draw attention compared to the relatively low key “update” that fan pages will offer. There are no Mass-messaging or event options in Facebook profiles so this is the major distinction in terms of marketing functionality.
Caveat, if your group has over 5,000 members you will not be able to invite members of a host group to an event.
For branding purposes you definitely need both a Facebook Profile and Fan Page.
Now, it is odd that Facebook implemented these two types of accounts with such limited capabilities instead of a unified group with the capability of being seen publicly etc. My recommendation is that you create a fan page and focus the group on relevant discussions. The primary advantage of a Group is that these will offer the ability to message all the members via Facebook mail. A Facebook page’s mass message will come as an “Update” which is harder to notice.