Smoke is a dedicated editor competing with Avid’s high end editing systems. While it is an editor, it still offers alot of the functionality of the Flame/Flint/Inferno Systems. But it lacks alot of the roto/paint tools that the compositing systems offer.
You wouldn’t really want to say, edit a tv series on a FFI machine. It’s really all about providing tools for different people, while there is alot of overlap, you put your editor on a smoke machine, your roto and compositing guy on a FFI machine. If you’re working on a feature film you’ll have someone on a lustre system grading all of the finished/rendered shots.
And then of course if you just need large volumes of tedius work, without really any need for real time client input. You dispatch individual shots to Combustion/Shake.
Lustre is like Vympel said, dedicated to color correction, mostly 2k and 4k stuff. It does actually offer blurs and some other effects. But it’s not designed around that kind of work, it mostly just takes finished composites and ensures they match the shots that didn’t go through a compositing suite.