Direct3D vs. OpenGL

From DmWiki

Beginning graphics programmers often ask whether they should learn DirectX or OpenGL. However, DirectX cannot be compared with OpenGL because DirectX is a Windows-based suite of libraries (including input, audio and graphics libraries), while OpenGL is a cross-platform graphics-only API. A comparison of OpenGL and Direct3D would make much more sense. So what are the differences between Direct3D and OpenGL?

Direct3D vs OpenGL
Topic	Direct3D	OpenGL
Language	Uses C++ (object-oriented). Also available in C, and all .Net languages	Available in C, Java, Assembly, Pascal, and other languages
Immediate Mode?	No immediate mode	Has immediate mode
Platform support	Used on Windows, XBox, XBox 360, foundation for XNA	Used on Windows, Linux, MacOS, Gamecube, Playstation 3 (OpenGL ES subset), Silicon Graphics Workstations, BeOS, others
Utility Library	Has extensive helper library, D3DX	Has a smaller utility library GLU, which provides less high-level functions, but the language is capable of performing many of these functions low-level without the need of high-level interfaces.
Extensibility	Direct3D 9 uses CAPS (capabilities bits) to query supported features, Direct3D 10 requires all features to be supported.	Utilizes extension loading to access advanced features.
Hardware Acceleration	Cannot use hardware features that the API does not support (updated once every 2 months)	Can use hardware feature that API does not support (requiring different code paths for e.g. nVidia (http://www.nvidia.com/) and ATI (http://www.atitech.com/) cards)