Prejudice and racism are two very different things. They are related, but they are not the same thing.
Prejudice is an unjustified or incorrect attitude or opinion, usually based on stereotypes, that one holds about another person or group. Racism is the belief that one race is superior to another, or the practice of treating someone differently based on their race.
When someone says “I’m prejudiced against [group]”, they mean that they have a negative opinion of people in that group. When someone says “I’m racist towards [group]”, they mean that they believe that the members of that group are inferior and deserve less respect than other groups.
Prejudice can be based on race alone, but it can also be based on other factors such as religion, gender, or sexuality. Racism is always based on race – it’s impossible to be racist towards someone because of their religion unless you think that religion makes them inherently inferior to people who don’t have that religion (which would be prejudice).
Prejudice can be positive or negative.