Leak Tracker for PT4 will give you some general stat ranges, and will give you a good/bad type grade, but it doesn't go in depth at all.
Leakbuster gives you alot more in depth analysis, and has a lot of features, full length video content, written content, Steps for Preflop, Position, Trouble Hands, Biggest Losses, etc. 42 Filters that you can run, and will pull up hands from your database. They really aren't comparable, and i don't think it was meant to try and compete with Leakbuster. I have even seen the Poker Tracker guys recommend Leakbuster to players that need more in depth analysis.
IMO just the video content alone in the program is worth the price. But there are alot of other cool features.
For me, it has been one of the best things i have used. I actually first bought it for PT3/PT4, but then switched over to HM2 and ended up buying it for HM2 as well. i run it after every session.