Linux 13.8 Beta = 13.8 Beta drivers with OpenGL 4.2 files
OpenGL 4.3 Beta = 13.8 Beta drivers with OpenGL 4.3 files
The OpenGL 4.3 might not be ideal for users of certain OpenGL programs, so they split the two up until the next release, ensuring that newer drivers for display was available for OpenGL 4.2 users, and that the OpenGL 4.3 compatibility was available for those who want it. Basically the OpenGL is a slightly newer release, since it has 13.8 plus newer OpenGL.
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