You know, I remember back in December reading on TORN, that FOTR got a 15's rating in some Scandinavian country; Norway or Sweden I think. It was also very close to getting a 15's rating in the UK, but instead the censor made it PG-12's but for only the second time in British movie history, an extra advisory warning was issued pointing out high levels of 'strong fantasy violence'.
Seemingly, the way it works is thay violence in a fantasy context is not as bad as say somebody getting their head chopped off in a war movie, or in a violent thriller.
Also, LOTR had no sex/nudity/strong language. So while the violence would have been R in any other movie, because it was fantasy and had no sex/nudity/language at all, it managed to get the PG cert.
yes... I think the type of violence and the setting is important... showing an imaginary type of evil creature get beheaded is different than showing an innocent victim get beheaded.