The principle of “managing” is to get things “done”. There is no doubt that in order to get things done in complex organisations today, modern leadership skills are required. So instead of narrow labelling of professionals into manager or leader I prefer to measure how succesful managers are, and succesful managers are strong leaders by definition.
This logic does not hold the other way though, fantastic leaders are not necissarily great managers. Often visionary leaders require a team of strong managers around them to execute their dreams.