Kitchen sink settings. Like Greyhawk, FR, and Mystara.
This doesn't mean that they are generic (although they are sometimes referred to as such), this doesn't mean that they aren't quirky, this doesn't mean that they aren't different from each other (more high fantasy, more swords and sorcery, etc.). Instead, it only means that it is a large, multi-purpose setting that can accommodate a diverse number and type of "standard" D&D adventures and tropes. In other words, if you choose this type of setting, it would be fairly simply to quickly adapt any standard D&D module or AP to fit somewhere within it.
POV settings. Like DL, DS, Eberron.
A POV setting is a setting that is the result of a particular POV; it usually has modest or severe departures from the standard races and classes of D&D, along with a distinctive milieu that is not just a fantasy sandbox. A campaign in this setting should be taking advantage of the unique features of the setting.
Meta settings. Planescape, Spelljammer.
PS and SJ are "settings," but they are also explanations for the interstitial space between campaigns. You can have a campaign set in any other particular setting that is also a part of a meta setting.
Any way, that's how I view it.
