Greg applied for a position as a senior software engineer at a company but was rejected in favor of a female candidate, Lisa. Greg finds out that his qualifications and experience were better than Lisa's, but she was hired as a part of the company's affirmative action efforts. In this case, Greg may have experienced

Reverse discrimination.  

Explanation:

Reverse discrimination is defined as  the discrimination  of targeting the members of a minority or dominant group.For example In Recruiting the decisions in support of the minorities group, given in the background  of candidates from the male or another minority group.

According to Greg points out that his qualifications and experience were higher than those of Lisa, but she was recruited as part of the affirmative action activities of the organization.Greg also is a senior software engineer in the company  but he was refused in favor of the female candidate Greg has experience of the reverse discrimination.