DEI defined:

Source: https://www.diaglobal.org/
“Diversity”
The practice or quality of including or involving people from a range of different social and ethnic backgrounds and of different genders, sexual orientations, etc.
“Equity”
The notion of being fair and impartial as an individual engages with an organization or system, particularly systems of grievance. “Equity” is often conflated with the term “equality” (meaning sameness). In fact, true equity implies that an individual may need to experience or receive something different (not equal) in order to maintain fairness and access.
“Inclusion”
The practice or policy of providing equal access to opportunities and resources for people who might otherwise be excluded or marginalized, such as those who have physical or mental disabilities and members of other minority groups.