If you're just the watching the movie, there's about 3 minutes worth of difference. But comparing the two frame by frame, there's a LOT different. Some shots between cuts are extended or shortened by a frame or two (or in a few cases, some shots are actually edited in the middle by several frames). Now, don't get the wrong idea...I'm an iRiff maker, if you don't know, and I'm not normally this obsessive-compulsive (working on an iRiff for each version of the film...yes, I know Rifftrax made one, and no one here cares, but I announced it back in December, dammit!). But of changes that are obvious between the two:
1. About 8 minutes in: Robots attack them as they're searching. They blow them away and keep going.
2. About 16 minutes: Talk between Ironside and Bale longer, Ironside threatens Bale with a gun. Assuming this was originally a blooper they wanted to add back in as revenge for the rant (Kidding, kidding!).
3. About 50 minutes: The infamous segment of Bloodgood's sideboob. The scene really only exists for an R-Rating, it has no bearing on the plot (and there's not really much to see, since it's in the dark anyway).
4. About 52 minutes: The fight scene is extended by quite a bit, though not as bloody as you might think. A lot of little things here, but most noticeable are Worthington using a guy as a shield to protect against a shotgun blast, a longer look at the screwdriver in the arm bit, and some alternate shots of the guy getting shot in the leg.
5. After the fight scene: Some additional talking at the fire between Bloodgood and Worthington.
6. About 59 minutes: Alternate shot of the guy getting shot up by the T-600. You see about half a second of his back getting riddled with bullets.
7. About an hour 19: Christian Bale talks about his mommy. Amazing no one shut off their radios right then.
8. About an hour 39: The T-800 pounds Worthington two more times. Not much gore or anything, but I guess a robot hitting somebody with a gigantic block of concrete two times is okay for PG-13, but FOUR...
Those the are most obvious. Like I said, there are a LOT of weird, little cuts throughout the whole thing, but none of those are obvious unless you're REALLY looking.