Here are some helpful definitions to aid the understanding of related but distinct concepts discussed.

Diversity

At its most basic, diversity simply means variety. In nature, biodiversity refers to the variability of organisms within an ecosystem. This general concept applies to work, too.

At work, diversity means the presence of difference within our contained environments. We define this difference in several ways. For example, we may seek cognitive diversity $($diversity of ideas$),$ educational diversity, or demographic diversity. When we refer to diversity in corporate conversation today we often imply the latter, specifically in relation to the protected classes. The protected classes are groups protected by law against discrimination. These groups include men and women based on sex, any group which shares a common race, religion, color, or national origin, people over $40,$ and people with physical or mental handicaps. But we are all diverse in so many ways beyond legal definitions so don't limit your thinking to "categories". In fact if you think about it$,$ the existence of categories might be part of the challenge as in some instances we seek to ignore differences, but in others we seek to identify them when we seek diversity.