Not sure about the best thread, but here's an attempt to highlight the major changes briefly, in no particular order.
1.28-1.28C/D (D is really C with 1024x768 screens)
1. The use of external "dat" files such as "TMod.dat".
2. The "CDF.set" and "Dir.set" system which allows the exe to use custom CDFs and find needed files in nominated folders rather than having to move files into the EAW folder.
3. The ability to use 24bit bmp files for skins and terrains (D3D only).
4. Multiskins- entire squadrons with individual aircraft markings.
5. Gun convergence.
6. The use of convoy files which can determine the make-up of trains and both land and sea convoys. "Convoys.dat" in particular associates sea convoys with up to 255 targets, and contains set waypoints.
7. More interdiction mission types which are selectable in single missions and multiplayer.
8. Massive changes to multiplayer which give the host the ability to choose settings similar to those available in single missions. They also allow a player to join an existing mayhem, or to communicate with players already in a game if it is not a mayhem.
9. Single engine starts for engines 1, 2, 3 and 4, with "wet starts".
10. New aircraft selection screens (Allied and Axis), but with the ability to use the old "picpln" screens and menus through an eaw.setting.
11. More cockpit gauges.
12. A maximum of 256 TMods
13. An improved cockpit view system using files containing data which offsets the pilots head to optimise the views.
14. Single mission "encounters" so that if you are flying over an enemy base on the way to a target there is the possibility that fighters may scramble from that base.
15. Several new eaw.ini settings
16. Individual "Savedata" folders.
17. Artillery activity on land close to frontlines.
1.28E
The biggest change is that individual aircraft data can be used.
Those "30 plane" files such as "planes.dat" have been broken up into single plane files, to enable packages to be made. There are two types which work together in combination, one containing flight data, and the other containing graphical data. It is done this way so that although a user might choose an ETO, desert, or a South East Asian Spitfire V skin, the flight data will be the same.
It also uses 1024x768 screens, and a more flexible mainscreen menu system.
No final decision has been made yet, but it is likely that 1.28E will support a 128 objects per tile eaw_ttd.dat file rather than the old 64 objects per tile.
In all versions as soon as fixable bugs were discovered they were fixed

Jel