LB7 (01-04) 300HP, 560FTLB, hidden injectors, gated turbo.
LLY (04.5-05) 310HP, 590-605 FTLB, exposed injectors, VNT turbo.
LBZ (06-07) 360HP, 650FTLB, total engine redesign. No parts in common with LB7 or LLY.
The LBZ has many beefed up parts on it, as well as "tap-shift" 6-sp transmission. Better engine and trans, IMO.
NOTE: 2006 trucks marketed as LLY's (310HP) aren't. They are LBZ's that have a different program loaded. Why GM sold them that way is anyone's guess. True HP rating should have been about 335HP.