How do one-pipe steam systems differ from two-pipe systems in terms of radiator connections?

One-pipe steam systems have a single pipe that supplies steam to the radiator and returns condensate, whereas two-pipe systems have separate pipes for steam supply and condensate return. One-pipe systems require a specialized radiator design with a built-in steam trap and condensate return mechanism, whereas two-pipe systems use external steam traps and separate condensate return piping. This fundamental difference affects the piping layout, radiator design, and overall system operation.