Yes, it's time for a long-overdue post. I know I mentioned that I was going to cover this topic on at least two psychology posts and on another of my blogs, so here it finally is.
This is not mere semantics. This is not nitpicking about the way terms are used. This is informing readers about the real difference between prejudice and discrimination. This is also to inform readers that it is possible to have one without the other.
Prejudice: an attitude held about an individual and/or group of individuals based on perceived characteristics believed to be shared by the group. Prejudice is an attitude. I've already written about the different components of attitudes here. Remember, attitudes 1) are learned; 2) have three components (emotion, behavior, thoughts); and 3) are poor predictors of behavior. Notice, also, that a prejudice is simply an attitude. Although even college textbooks will throw in the words "primarily negative" before "attitude" in their definition, the truth of the matter is that prejudices can be positive as often as they can be negative. What makes a prejudice unique as opposed to other attitudes? Honestly, not a whole lot, except they do seem to be applied primarily toward perceived characteristics of other people, and not so much toward objects, though sometimes a prejudice may be formed about certain ways of thinking (like political ideologies). When we assume that people like us are favorable, we display a positive prejudice. When we decide we don't care for someone because they are "one of those people," then we display a negative prejudice. Prejudices are heavily influenced by stereotypes, which are in turn influenced by all the other circumstances--direct exposure, learning, second-hand hearsay, media, etc.--that lead to other attitudes. A prejudice can be changed, for good or ill, from positive to negative and vice versa.
Discrimination: differential treatment of individuals. Discrimination is an act. We are talking about overt behaviors (see a previous post of mine on what is considered a behavior). Notice again that there is not any sort of emotional attachment to the definition, although many text books include terms such as "negative" or "harmful" in their use of the term. On the surface, discrimination happens all the time. When you choose chicken over fish, you discriminate between the dishes, putting them into different categories and then making a decision based on the qualities of the categories and what you desire at the time. The same occurs, without violating civil rights laws, in employment when a company sorts candidates into "piles" based on their education, experiences, and skills and then select candidates who they feel fit the requirements of the job. Problems arise when discrimination, or differentiation, of individuals occurs based on stereotyped beliefs that have very little to do with necessity. Judging a person's honesty (this is a prejudice, by the way) based only on superficial things like their skin color or age and then treating them differently from others not in this perceived group (this is a discrimination) because of this judgment, is when things go wrong and fairness gets thrown out the window. It is possible to show "positive" discrimination. This is usually called favoritism, nepotism, or even reverse discrimination. It's still a form of differential treatment.
Can you be prejudiced without discriminating? Absolutely! Many people hold positive and/or negative attitudes about certain classifications of individuals and still choose to treat everyone as fairly as possible, to not let their preconceived ideas influence their choices. Unfortunately, our society has moved to a point that we want to control the thoughts and opinions of others. We now have a collective negative prejudice toward individuals who have prejudices. We stereotype anyone who uses a stereotype, even if said classification is honest or accurate. We assume that anyone who believes in a positive or negative stereotype is automatically going to unfairly mistreat others based on those thoughts. That's unfair treatment and stereotyping in itself.
Can you discriminate without having a prejudice? Sure thing! In fact, this is what is expected of us all the time. If you didn't discriminate, then you would date anyone who came along or hired any person who applied to the job even if they weren't qualified, or eat any food that was presented to you, or watch any movie that played at a theater. We differentiate between people and things all the time and it's not always tied to a stereotype-driven attitude about them. The intent and the thought process used are the key factors in determining unlawful or harmful discrimination or not. We also look for larger patterns to determine if a harmful discrimination occurred. Two is a coincidence, three is a pattern, four or more is a potential conspiracy.
It is okay to hold beliefs, positive or negative. That is your right, especially in countries like the United States that value individual freedoms. It is your actions and your intent with those actions that are subject to judgment to maintain as a fair a society as we can achieve.