How are Facebook pages different from Facebook profiles?

Facebook answers that question in the Pages Help Center.  Their answer:

Each user is permitted to maintain a single account, which is represented by a profile. Profiles can only be used to represent an individual, and must be held under an individual name. This account can also be used to manage multiple Facebook Pages that represent businesses or other organizations. You may only create Facebook Pages to represent real organizations of which you are an authorized representative, and fans of these Pages won't be able to see that you are the Page admin, or have any access to your personal account.

All personal site features, such as friending and messaging, are also for personal use only and may not be used for professional promotion. If you add a user as a friend, for example, this person will be invited to be a friend of your profile and not your Page. Using personal site features for professional promotion, or creating unauthorized Pages, may result in your account being warned or disabled.