Johnson
Johnson discusses the concept of power as a social hierarchy. This theory gives meaning to things (such as race, gender, sexuality, etc) that wouldn't have any meaning otherwise. When certain traits/characteristics are categorized and given meaning, people are able to understand their place in the world.
Johnson's diversity wheel demonstrates the idea that we can label people based on certain characteristics, but that only tells you the "social reality" of a person; it doesn't explain to you what a person's personality is like. People use differences to include/exclude certain people, which is entirely unfair because most of the characteristics are impossible to change. Johnson further explains this notion by describing "unearned entitlements" and "unearned advantages." We know that unearned entitlements are what every person should have, and unearned advantages are the restrictions placed on certain groups.
Johnson talks about the social construction of differences/reality. He explains how most of our "real" experiences are made up. And that unless you live in a culture that recognizes differences as meaningful, they're socially irrelevant and therefore do not exist. I think it's also important to note that history changes who is in and who is out as far as being privileged goes.