SDL_Rect (A SDL_Rect defines a rectangular area of pixels. It is documented in detail in the SDL documentation)
SDLmm::SRect (This enhanced version of SDL_Rect includes a number of handy short-hand constructors. Since the class is derived from the SDL_Rect struct, it can be used in any context where an SDL_Rect is valid)
SDLmm::Surface (A graphical surface structure which is used to store graphical data)