Waves Tune LT consumes the same amount of CPU and uses the same audio engine as Waves Tune, so it delivers the same sound quality.
The following features are disabled in Waves Tune LT:
MIDI receive

MIDI export

Natural vibrato detection

Synth vibrato.

Line, Curve, Glue, Cut, Pencil, and Hand tools

Tolerance and Range parameters

Scale editing

Acquire Session Start Time from Timeline
Finally, Waves Tune has 32 layers of undo; Waves Tune LT has 2.