Leadership and Politics are not interconnected, but people tend to connect them if they do not agree or doubts the decision made in there favor.
The difference is the way people think of decision made. Many a times in organizations we here "Internal Politics". All depends on the decisions. Decisions made are in terms of organization or self benefit. It depends on the person capacity to take up the decision as good or bad. Either self motive or organizations goals are base for making decisions.
Leader is a person who drives a team towards common objective. Leader is a part of team and not sitting on an above hierarchy and shooting orders. Leader is a person responsible to motivate the team, keep away from Bias, be a good listener, give and accept feedback. But, we cannot deny fact, Human demands are unlimited and supply is always scarce. Each and every demand cannot be met; every ones wishes cannot be met, which in turn give rise to "Politics".