There are two main differences, and these are purpose and focus. Research companies are often called upon to review external sources to unearth new, generalizable knowledge on a topic, while evaluators work to assess the effectiveness of a specific program, policy, or initiative (often internal). The focus for researchers is on what is happening or what is known. Evaluators, by contrast, look to discover how well a program or policy worked, whether objectives were met, or how an initiative can be made better.