This info comes from the commentary in this video: http://www.youtube.com/watch?v=kat_m_ROg34 - You can change your class by changing your Battlesuit (they level independently) - "Armies" (guilds) level up and gain access to items and abilities (IE: calling down a thumper or a Evac) - You can broadcast a quest/mission to your entire Army sending an invite for all of them to join. If they accept they will be added to your party and given a waypoint. - There is a generic pool of weapons for all classes, and unique weapons for each class - Your armor and weapons are fully customizable (Weapon IE: reload rate, clip size, fire rate, alt-fires) - Dynamic events based on Time of day, week, year. - Cities can be invaded and lost if players do not defend.
New Interview: http://news.bigdownload.com/2010/10/06/interview-we-chat-with-the-executive-producer-for-firefall/
One major difference though, it is in actual first person shoot where as TR used a first person UI but did dice rolls behind the scene. That and no Lord British, god I hate that guy.