The word prejudice refers to prejudgment: making a decision before becoming aware of the relevant facts of a case or event. The word has commonly been used in certain restricted contexts, in the expression 'racial prejudice'. Initially this is referred to making a judgment about a person based on their race, religion, class, etc., before receiving information relevant to the particular issue on which a judgment was being made; it came, however, to be widely used to refer to any hostile attitude towards people based on their race or even by just judging someone without even knowing them. Subsequently the word has come to be widely so interpreted in this way in contexts other than those relating to race. The meaning now is frequently "any unreasonable attitude that is unusually resistant to rational influence". Race, sex, ethnicity, sexual orientation, age, and religion have a history of inciting prejudicial behavior.
A bigot is a person who is intolerant of opinions, lifestyles, or identities differing from his or her own, and bigotry is the corresponding state of mind. Bigot is often used as a pejorative term against a person who is obstinately devoted to prejudices even when these views are challenged or proven to be false or not universally applicable or acceptable.
Racism, by its definition, is the belief that race is the primary determinant of human traits and capacities and that racial differences produce an inherent superiority of a particular race. People with racist beliefs might hate certain groups of people according to their racial groups. In the case of institutional racism, certain racial groups may be denied rights or benefits, or get preferential treatment. Racial discrimination typically points out taxonomic differences between different groups of people, even though anybody can be racialised, independently of their somatic differences. According to the United Nations conventions, there is no distinction between the term racial discrimination and ethnic discriminiation.
They all mean similar, yet different things as you can see.