As you said it is different resources. There are method differences, one is always better for your card. The DirectX is more compatible the OpenGL. I not really know the OpenGL technology.

But for answering your question, there are not quality difference on the same settings. I think the DXD has less system requirements.

Thanks :)
I hear Nvidia cards are better with OpenGL, and I don't think it will change performance under a gtx980ti. I'm so glad I can play it on windows 10 now!

You're welcome. Yes, the NVidia likes more the OpenGL for some reason. My old WinXP isn't really makes performance differences between D3D and OpenGL when I play on UT2004 or the Half Life 1. :)

Someone should make a thread and get it stickied.
If you get Device lost error in Windows 10 then:
http://pcgamingwiki.com/wiki/Unreal_Tournament_2004#D3DERR_DEVICELOST_error_under_Windows_10

I agree, this fixed my problem. Win 10 64

It will still crash after doing that as Windows 10 dx12 does not support dx8 games to run in exclusive full screen anymore. Check it out yourself with any capture software, all software will report a window called ut2004 instead of a game source. DX8 games get forced to run in full screen windowed without borders modus. Due to this some mouse and color feautures do not function or cause the game to crash.From the default.ini you still need to change a mouse option in the ut2004.ini to get it running without a crash in full screen. Would indeed be nice if Epic updated the .inis on Steam so people can launch without guaranteed issue.

goo.gl/maoapk