The cut british DVD (BBFC 15) has been compared to the uncut American DVD (rated R).
1x longer opening on the British DVD
2x alternative, more brutal footage shown on the US DVD
Runtime difference (not counting the opening) 1.07 sec.
In Horns, by Alexandre Aja, Daniel Radcliffe continues to attempt to get rid of his image as a young apprentice wizard. He plays his character, Ignatius Perrish, very seriously, angrily, and bitterly due to the death of his one true love. In doing so, he acts against Aja's intention to give the film a dark-humorous and cynical touch as well as a sometimes even relaced voice.
The British theatrical version was slightly cut in favor of a lower rating. Instead of an 18+ rating, which was given to the uncut version aftwerwards, the theatrical version was rated 15+. Two shorts scenes were alleviated to allow for this. Among those, the most "bloodthirsty" scene of the film during the final twist. Considering the film's staging, this short shot in which a man's head is blown away with a shotgun seems rather misplaced, either way.
Both cuts are remarkable as, while the BBFC 15 version is shorter in those places, it features alternative or other extended and more harmless shots. Apparently, there was access to more footage than what is contained in the uncut version.
The British DVD begins with the Lionsgate opening whereas the US DVD starts with RADIUS TWC.
In the British version, you can see Merrin defending herself against Lee a bit longer (flashback). Afterwards, Lee is shown (present time). In the US-version, Lee forces himself between Merrin's legs (flashback). Afterwards, Lee tells Ig "I fucked her tight little pussy" (present time).
After the shotgun goes off, the cut version cuts off and you see Eric instead, falling backwards (no blood). Lee and Ig watch in disgust. In the uncut version, you can see the bloody details of Eric's head being shot off and the body falling to the ground. Afterwards, the shot of Lee and Ig begins and both versions run in sync again.