Influence is the actual capability of swaying the course of specific actions. Individuals can be powerful, influential, and a leader, but they do not necessarily have to be all three. There are two basic models of community power. Elitism and Pluralism. Elitism means that power and influence are strongly centralized.
Power resides in the hands of a single individual or just a few people.
It is almost impossible for elitists to be indifferent on any issue. There are two main types of elitists, one based on wealth, and one based on the electoral process. I would argue that they are basically the same thing. Pluralism is similar to Elitism. To me, Pluralism is a little community of elitists.