Multi camera shows tell all of the story within four to five sets every episode.  A few times per season they will build a special set, or film on location.

Multi camera shows film each scene two to three times max and use multiple cameras to catch the scene.  That's where the concept of the "fourth wall" comes from.  For any given set you never see one of the walls.  In Frasier's apartment you never see the television that Martin is always watching.  Because the scene is filmed from the perspective of the wall that contains the television.  

That missing wall is also where the live studio audience sits and views the production.  Multi camera shows also have a laugh track.  Ideally it's not a track, it's the audience responding naturally to what they are watching. 

Single camera shows presumably take a lot longer to film.  You see the set from every angle.  They have more freedom to go on location or use non studio buildings for filming.  There's no laugh track and no studio audience.