Operational: Person with whom you interact in your current role (eg. those who provide information, make decisions, and/or help you maintain current capabilities).
Personal: Person to whom you turn for personal and professional development (e.g. those you reach-out to for general mentoring to find meaning in your work, or to help you rejuvenate or refocus).
Strategic: Person to whom you turn to figure out future priorities and challenges; building stakeholder support (e.g. those who help spark your thinking to develop creative or innovative approaches, focus on reaching long-term goals and/or make sense of the political or informal network).