An agency’s Equal Employment Opportunity (EEO) officer works in that particular agency and deals with government employees only. An investigator at EEOC can investigate claims from private and government employees.
Both of these professionals have to power to require documents, take statements from witnesses, apply laws, and render legal decisions. Although the EEO officer works for the agency, he or she is required to be neutral and to produce a decision that is in line with what the law. That neutrality is also required of all EEOC investigators.