It is always prejudice. If you are judging a person based on a classification and not them as an individual on their merits that is prejudice by definition. The thing is, all hiring includes prejudice. It is impossible to completely remove. The reason is that we all have experience or are influenced by the opinions of others. This is why many firms have hiring committees to try to level out prejudice.

Having said that following the pattern of others is easier than breaking the pattern. The risk reward ratio skews to following "best practices".