Am I a high performer?

The term "high performer" is one among several synonyms that include star employee, star-performer, top-performer, high achiever, high-potential, game-changer, pace-setter, supremely-talented, and someone who's knocking it out of the park. CredPad prefers the term "contributor." Contributors or high performers can be found in a variety of roles in every industry.
What differentiates high performers from others? High performers make significant and demonstrable contributions to corporate-level success. An HBR article says high achievers are "400% more productive than the average employee." Those who believe the 80/20 rule say high performers constitute the top 20% of employees in an organization.
Is a contribution different from an achievement?

If you played a significant part in a specific organizational success, you made a contribution. Your contribution is in terms of the effort you put in and the results you delivered that became a significant part of that success. The recipient of your contribution can be any well-defined and sizable organization or community (community could be a profession, industry, country, or the world).
Is "achievement" different from contribution? An achievement is something uncommon that is accomplished using uncommon ability. Yet, it has a personal ring to it — until it rises to the level of a contribution when it makes a significant impact on an organization or community. For example, publishing a book is an achievement no matter what, but if there's evidence that the book improved, say, customer acquisition at hundreds of businesses, then it is a contribution to the business community.