Since I have only been playing the Red Falcon (modded over Falcon 4.0 Allied Force) I can't say what the diffrence is from it to Allied Force or Open Falcon. I tried use open Falcon today and found that unlike Red Falcon Open Falcon will not mod over Allied Force, I don't know if it was caught in my earlier post but Falcon 4.0 [Vanila] (microprose) is the base, Allied Force (is Lead pursiuts modded version of Falcon 4.0 vanila bought from micropose and sold on shelves at stores), Red Falcon is a mod of Falcon 4.0 vanila that can be put over Allied Force (though only effecting Korea not balkins) and Open Falcon is yet another mod of Falcon 4.0 Vanila but it can only be put over the vanila. with all that in mind today I got the Vanila microprose Falcon 4.0 so that I could try out Open Falcon to see the diffrence in it verus Allied Force and Red Falcon. with all thatin mind this is my understanding of the biggest diffrences (still downloading Open Falcon as I type) Falcon 4.0 Vanila (Microprose) you play 1 theatre in Korean campaign circa 1983 this version has very poor graphics (its old) and is buggy. Falcon 4.0 Allied Force (Lead Pursuit): lets you play in two theatres either Korea or the Balkins, The Korean Theatre breaks down into 3 campaigns which are Korea 1983, Korea 2005 or Korea Euro war (which also takes place in 2005) Graphics a new and improved flight dynamics a more advanced Falcon 4.0 Red Viper: has the Korean Theatre only with three same three campaigns as Allied force, but its focus seems to be with a better flight model than allied force and excelllent graphic detail of plane models and terrain, all I know about Open Falcon for now is that its the same essentially as Red Falcon but instead of graphic (which are still good) its focus is on flight mechanics and simulation detail I.E. all the buttons in the cockpit work exactly as they should. now Red Falcons cockpit buttons work as well at least in the 2d cockpit you can see them operate and in the 3d virtual cockpit they aslo operate but don't move. where as I believe in Open Falcon they move and work in both. I'm about to find out for sure. Here is a link to try to help
http://forums.frugalsworld.com/vbb/forumdisplay.php?f=3 I'll try to update and let you know more about Open Falcon it's done DL'ing now, oh and I almost forgot in Red Viper and Open Falcon you can fly with any sqaudron and in any plane in the campaign not just the F-16, I know also that some of them have the correct cockpits both 2D and 3D some cockpits are better than others, but some planes like the C-130 still use the F-16 cockpit, you can DL other cockpits (like the C-130)
Okay an update: From limited play of Open Falcon I found the Cockpit Graphics and use of the cockpit to be far superior to Red Falcon (though Red Falcon's are great) as Open falcon 100% of the buttons work Red falcon is 90% (somethings that you never use like cockpit heat) however the Red falcon Cockpit opens and closes and Open falcons does not... that being said Red falcons sounds in and out are better its graphics outside the cockpit are better, RF aslo has better 3D cockpits for most of the other planes.