15 and 18 rated films

15 – Suitable only for 15 years and over

Language
There may be frequent use of strong language. But the stronger terms will be acceptable only where justified by the context.
Nudity
May be allowed in a sexual content but without strong detail
Sex
Sexual activity may be portrayed but without strong detail. There may be strong verbal references to sexual behaviour.
Violence
Violence may be strong but may not dwell on the infliction of pain or injury. Scenes of sexual violence must be discreet and brief.
Imitable Techniques
Dangerous techniques (eg combat, hanging, suicide and self-harming) should not dwell on imitable detail. Easily accessible weapons should not be glamorised.
Horror
Strong threat and menace are permitted. The strongest gory images are unlikely to be acceptable.
Drugs
Drug taking may be shown but the film as a whole must not promote or encourage drug misuse.

18 – Suitable only for adults

Language
More frequent use of expletives
Sex
Sex is portrayed as a common thing
Violence
More commonly used as it creates a way for one character to get revenge on another
Drugs
Used as a way of characters relieving stress

This informaion was obtained from the BBFC website. For more information ...
http://www.bbfc.co.uk/