Defining Purpose Driven
A purpose driven organization is one that explicitly measures success with a metric(s) other than shareholder returns. Purpose driven organizations exist to create some other change in the world, and that goal is made explicit throughout the organization, including to shareholders.
Non-profits, foundations, community and religious organizations and some for-profit businesses are all purpose driven organizations. A for-profit business is purpose driven when the company explicitly trades off long term shareholder profit for other goal(s).
Purpose driven investors invest in purpose driven organizations, and track their own success on metrics other than investment returns.
More on the taxonomy of purpose driven organizations here, including tradeoffs and tensions within various organizational models.