They are two sets of regulations: the Employment Equality (Sexual Orientation) Regulations 2003 and the Employment Equality (Religion or Belief) Regulations 2003 which outlaw discrimination in employment and vocational training on the grounds of sexual orientation and religion or belief respectively
The Sexual Orientation Regulations apply to discrimination on grounds of orientation towards persons of the same sex (lesbians and gays), the opposite sex (heterosexuals) and the same and opposite sex (bisexuals). They cover discrimination on grounds of perceived as well as actual sexual orientation (i.e. assuming - correctly or incorrectly - that someone is lesbian, gay, heterosexual or bisexual). The Regulations also cover association, i.e being discriminated against on grounds of the sexual orientation of those with whom you associate (for example, friends and/or family).
The Religion or Belief Regulations apply to discrimination on grounds of religion, religious belief or similar philosophical belief. They cover discrimination on grounds of perceived as well as actual religion or belief (i.e. assuming - correctly or incorrectly - that someone has a particular religion or belief). The Regulations also cover association, i.e. being discriminated against on grounds of the religion or belief of those with whom you associate (for example, friends and/or family)
The Sexual Orientation Regulations do not cover discrimination other than discrimination on grounds of people's (actual or perceived) sexual orientation.
The Religion or Belief Regulations do not protect against discrimination on grounds of belief not akin to a religion or similar philosophical belief, e.g. being a fanatical supporter of a particular football club, or being a supporter of a particular political party because of strongly held political views.
The Regulations apply throughout the employment relationship - during the recruitment process, in the workplace, on dismissal and, in certain circumstances, after the employment has finished.
The Regulations apply throughout the vocational training relationship - during the application process, in the place of training, and in certain circumstances after the vocational training has finished.