Also, the sole flight of the Buran was entirely unmanned - unlike the Space Shuttle, which had less sophisticated automation and required a pilot onboard to land the thing, Buran was capable of entirely automatic landing. The difference was probably mostly the result of political rather than technical reasons though.
The only reason Space Shuttle has required a pilot when landing from the point when the re-entry burn has started was to push a button that lowered the landing gear at a proper point in time. In fact, there was some equipment stored on the ISS that, if installed, would allow the Shuttle to land autonomously (the intended use for that was deorbiting a Shuttle with significant tile damage).
It is unclear whether Buran's autopilot is more or less complex than the Space Shuttle's fly-by-wire system. The pilot's inputs are the outer loop of a very complex feedback control system on the space shuttle; one need only look at how stable SS Columbia was on its last re-entry (despite heavy damage,) to appreciate the fly-by-wire system.
