Compared was the unrated LaserDisc by New Line Home Video with the unrated DVD by New Line.
There are 6 differences with a total length of 1 minute and 36 seconds:
2 cuts = 27 seconds
4 alternative scenes = 1 minute and 9 seconds
The history of the versions of TCM III is rather complicated: the movie had to be heavily censored for the theatrical release in order to get the more profitable R-rating. This already pre-censored R-rated version from the USA was then also released in other countries. The first unrated version, which was at least considerably longer than the R-rated, came out on VHS and LD soon afterwards in the USA. But it quickly came to light that this unrated version didn't contain all scenes, either. Among others, a VHS was released in Spain which was still a bit longer and apparently cut differently.
So when the medium DVD became popular there was released, at first in the USA, then also in GB, a new unrated version (the R-rated version is also contained on both discs). This second unrated edition is also called "News Lines Unrated Version". When comparing the unrated first edition (US VHS / LD) with the unrated new edition (US / UK DVD) it becomes clear that the new edition is more revealing and hence is probably the best choice at the moment. Some changes were made during the hammer scene. On the unrated DVD, the little girl gets to kill Ryan with the hammer. But all shots of her in this scene are missing on the LaserDisc, which is supposed to suggest to the viewer that not she but Tex killed poor Ryan.
At the moment, it's unclear in how far the already mentioned Spanish VHS tape differs from the two unrated versions. Unfortunately, the tape wasn't at hand, so this couldn't be checked (if one of our readers could provide us with this tape, he or she may contact us via E-Mail). Apart from the already mentioned versions, there's also circulating a rough cut of the movie, which apparently contains the most scenes, however, as is usual, it's not an official version and only available in poor quality.
All in all, there are at least 5 versions of TCM III: R-rated version, unrated first edition (US VHS / LD), unrated new edition (UK / US DVD), Spanish VHS by Columbia Tristar, rough cut.
The remaining runtime difference between LD and DVD is due to a different playback speed.
Tex says to Michelle that they used to have problems with smashing the heads of their victims, but thanks to Tinker, they now have a new hammer construction, which makes this a lot easier. Then he walks to the oven and lifts the lid off the pot. After that, Tinker is shown fiddling with something.
The little girl runs into the kitchen and says in a loud and angry voice to Tex that he has promised to leave the next victim to her and that he is breaking this promise right at that moment. Tex and Tinker give her permission whereupon the girl happily runs to Tex who then puts her on the kitchen cupboard. He tells her that he will count to three, then she shall pull the line of the hammer construction. And so they do it then. As alternative the LaserDisc has Tex explaining to Michelle that the smashing of the skulls was always quite complicated and that they now have a great hammer construction for doing so. This scene was already missing a bit earlier and was reinserted here. Moreover, there's an additional shot of Ryan hanging upside down and of Michelle, who is gagged and tied to a chair. Both versions set in again at the same time when the line is pulled.
LD: 12 sec.
DVD: 70 sec.
On the LaserDisc, there's a shot of Ryan hanging upside down. The DVD shows the hammer shooting towards Ryan's head instead.
LD: 1 sec.
DVD: 2 sec.
After Ryan got killed with the hammer the others are shown rejoicing over this.
Ryan's blood is collected in a cup standing under him. In the meantime, Tinker approaches dead Ryan with a knife. After that, the little girl takes up the blood-filled cup and hands it to Leatherface. The LaserDisc version shows a shot of grandpa instead.
LD: 2 sec.
DVD: 12 sec.
Tinker can be seen longer. Then it's shown how the mother dies and how she lets her hand drop. Her death is displayed slower on the LaserDisc, hence there's no running time difference.
No runtime difference