The Buran was "just" a shuttle with smaller built-in engines that attached to either the Energia rocket or a enormous carrier plane to be carried into space/the upper atmosphere.

Buran was able to perform an automated light around the world all on it's own, it was the space shuttle perfected that could have been used to e.g. establish a research base on the moon since it was able to carry a lot of cargo and could be reused much more often since the wear was on the discardable Energia rocket system.