As has been stated already
Cubase = Music Production
Nuendo = Film/Post Production
Samplitude = Music Production
Sequoia = Film/Post Production
Pro Tools = Music Production
Media Composer = Film/Post Production
It's a common theme, and scheme, among the "heavy players"...
The bottom line is that the latter of each is "more expensive" due to their ability to "do more" for the intended
market.
So, if your sole intent is "producing music" then Cubase, Samplitude, Pro Tools, etc..would be all you need.
However, if you intend on doing "Film Scoring/Post Production" work, then Nuendo, Sequoia, Media Composer
is the vehicle those who do such work prefer to "ride in"....
Can you do that in the others? YES - but with limited functionality in that regards,
but that's really not what they are intended for.