Difference Between Omniture DataWarehouse and ASI slots

Many first time users of Omniture SiteCatalyst have this question as to what is the difference between DataWarehouse and ASI slots. Infact ASI slots is part of Omniture DataWarehouse. However there is a major difference between the two -- whereas DataWarehouse is ideally used for ad hoc analysis (mostly one time requests), ASI slots are created for segmenting your traffic and using all your SiteCatalyst reports on this segments.