sdl is actually known as scsdl to avoid a namespace conflict on Windows.
sdl contains no utilities.
The sdl package is marked as Compatible, which means any game can use it.
SDLGraphics is the standard cross-platform GraphicsDevice implementor. It tries its best to adjust the screen to sRGB before proceeding (to disable, set NO_FIX_GAMMA=1 in the environment). It will try to use OpenGL when simulating a different-sized framebuffer via the true_width and true_height parameters. You can disable OpenGL and force it to use software by setting NO_OPENGL=1 in the environment; be warned that the software implementation is lazy and will not have correct results when doing partial updates.
A future version of SDLGraphics will support additional joystick-related functions.
SDLGraphics has no methods it didn't inherit.
SDLSound is the standard cross-platform SoundDevice implementor.