It contains such diverse tools as:
REAPER and Ardour and ProTools - Multitrack recording tools, used for recording live performances, with some basic MIDI capabilities built up over the years.
Cubase and Logic - MIDI sequencers, with multitrack capabilities accreted over many years to the point where multitrack recording (in the same contexts as the above category) is not unheard of, though the UI focus is different.
Fruity Loops and Ableton Live - Loop composition tools (for lack of a better description). Both are designed around loops as the basic building block of sound. While they have limited recording and MIDI capabilities, one likely wouldn't use FL or Ableton to make a symphonic soundtrack for a film, and certainly wouldn't use either to record a full band of performing musicians.
Renoise and apparently Radium - Trackers for the current century. These evolved out of the old Soundtracker style music programs (including Protracker, MED, etc. on the Amiga and then onto FT and Impulse Tracker on early PCs). They've acquired most of the functionality one expects from sequencers and loop based music programs, but don't usually have any multi-track recording facilities.
All are called DAWs by their developers and users, and yet how one uses them is pretty different. I pretty regularly use Ardour and REAPER for multitrack recording. And, I occasionally use Fruity Loops and LMMS for tinkering with remixes. And, I occasionally use Renoise for making electronic music.
I'd like it if there were separate terms for each of these concepts, as it would give folks a good language for talking about what each of these types of tools do. It would also rule out a lot of the stupid confrontational crap that often comes up ("Your program sucks because I can't do X, Y and Z, and I only ever use this other program!" where X, Y, and Z are functions specific to one of the above types of DAW...like "I can't easily do loop-based remixes in ProTools. ProTools sucks!").