ldpi: low-density screens (~120dpi) mdpi: medium-density (~160dpi) [baseline] hdpi: high-density (~240dpi) xhdpi: extra high-density (~320dpi)
there are also screen size qualifiers, small, normal, large, extra large.
AFAIK, the density qualifiers are still being used, and are mentioned in the "new" design guidelines document as well, giving me the impression they may stick around for a while. http://developer.android.com/design/style/devices-displays.h...
there are also screen size qualifiers, small, normal, large, extra large.