Compared are the shortened UK-DVD by FILM 2000 (BBFC 18) and the uncut German DVD by M.i.B. (not rated)
Difference: 59 seconds in 8 scenes.
In the UK, this Mario Bava slasher from 1971 was released cut on VHS (by Redemption) and DVD (by FILM 2000). The Uncut Version was relased on VHS, DVD and Blu-ray as well. The uncut VHS by Fokushin is very rare though. It's also a collectable because it's one of the infamous "video nasties"; even today.
The remaining difference results from the different pace (fps).
The shot of Brunhilda getting her throat slit with a sickle has been removed.
Subsequently, she gets a heavy blow in the neck. Blood splatters.
Extended shot of Robert with the hatchet in his face. He sinks to the floor. Then the killer removes the hatchet from Robert's face and pushes the body aside.
When Denise and Duke get impaled in the bed, a close-up of the spear in Duke's back is missing.
Shot of the impaled couples' struggle.
Same here. The VHS Version only contains the last part when they're lying dead on top of each other.
When Federica gets beheaded, the tracking shot of her neck spilling blood is missing.
Extended shot of Albert ramming the spear into Simon's belly who screams in agonizing pain.