Xbox 360 (Core): The original non-HDMI version of the Xbox 360.
Xbox 360 Arcade: Arcade models, which include an HDMI output.
Xbox 360 Elite: includes a 120 or 250 GB hard drive and has a matte black finish.
Xbox 360 Pro: included all the features of the Xbox 360 Arcade and included a hybrid composite and component cable with optional optical out instead of a composite cable.
Xbox 360 S (Slim): Xbox 360 S consoles feature redesigned internal architecture with the Valhalla motherboard, which allows for around 30% more space than previous motherboards, and the XCGPU, an integrated CPU/GPU/eDRAM chip using a 45 nm fabrication process.