Technically how I see this. (I can be always wrong ...)
There is no differences between GPP, 1.1.0 and TremZ, only advantage what TremZ is offering so far is possibility that with one client, you can play both versions.
Basically whole (98%) TremZ gamelogic part (cgame, game and ui) are based on GPP rev. 2260.
Only advantage what TremZ can offer over GPP are better game assets (models, sound ...) stuff like that, and ofc you can share game assets between versions.
Other advantages what TremZ can offer are more engine based and shared between game logic, so you can use Newton Dynamics, SQL, Ruby, IRC ... (stuff like that) on GPP and Tremulous 1.1.0 without problem ...
I can even share some info about that.
XreaL engine have "Bullet Physics" as collision detection, body dynamics ... So far how I see that, its used only on "shooting box" test.
--- TremZ with "Newton Dynamics" is providing "func_dynamic" for dynamic entity what are controlled by realtime physics simulation. In that way mappers can create in DarkRadiant (or what they are using for creating maps) special map object what are controlled via Newton physics. Rest object at map will be controlled on standard way.
Downparts of that are that at this moment, full support is done with Newton 2.00 and beside Linux (both x86 and x86-64), only x86 versions of MacOS and Windows are supported.
--- SQL. SQL is based on some previous work what somebody provided here (I really do not remember who that was and I apologize for that). His approach for was that SQL was server based, so I have changed that and prepared it for global centralized database.
To provide more info about that...
It may look like then "admin" will have ultimate power. Whole idea was that player can create his profile and use it in game like in some PHPBB based site.
While creating his game profile, he need to add common info (nick, email ...). With creating profile, MySQL write that in table along with players other details (XP, K/D ratio, levels ...), as dawn part of all this I wanted and planned that SQL record other stuff and provide in user details (how much he was kicked/banned/warned) so others can just use find and read on his userinfo page.
Other advantages of MySQL are that you can also send friend request and messages over system.
So far what its done with MySQL, is that game can connect on some specific address, create tables if they are not present alreay, write player name, GUID, ban/mute status ...
Downpart of all this is because of OpenSource spirit whole code "must" be released, and if I provide my MySQL password and server location, bad things can happen. Currently I am not too much happy with that, so if something will be changed there, is that whole MySQL stuff will be relocated in separate plugin and only source code to be shared on request.
--- MacOS support. It's hard for me at this moment to support client for MacOS. I don't have MacOS and VmWare and AMD Phenom what I have do not cooperate how I would want, and because of that somebody other will need to provide compiled files for MacOS X. Also code was updated to support iPad version, but I never tested it and see is it really working.
All iPad code was based on "Alexander Pick" work on Quake3, so it should work.
http://www.youtube.com/watch?v=2PBpxQKtSTA--- Ruby. Is used for better server management, don't get too excited. In future all that will be moved in separate plugins (along with LUA).
Currently I am having problems with x86-64 Windows version, because I cannot find library files for ruby-1.8.6.
--- OpenAL. Whole sound system at latest revision is based on ioQuake3 and Tremulous. Sound system for ETMAIN is broken in favor of Tremulous GPP and 1.1.0. Only thing what's different from ioQuake and Tremulous is that OpenAL is relocated in separate plugin (snd_openal.dll). If it is present in system, engine will load it automatically (no more cvar to set to 1), if not, system will use old.
--- IRC. Well it's interesting at least for me. I liked idea that you can automatically connect from game to some IRC server and chat chatroom <> game. All settings are ofc engine based. Client can choose random cl_IRC_server (irc server), cl_IRC_channel (what channel he want to connect), cl_IRC_port (port), cl_IRC_nickname (nickname for IRC channel) ... stuff like that. Ruby was added mainly for this. With ruby I can add some crappy script where you can be auth. and use RCON commands from IRC channel.
--- Internet shoutcast. Most interesting stuff at least for me. While playing ET I was really interested in possibility that while you are playing, you can listen some internet radio station. Currently its poorly added and only for Windows. Whole shoutcast it's done via BASS library and at this moment radio is hardcored in engine (in future it will be changed for sure).