RESPONSIBILITY SEGMENT - A significant organizational, operational, functional, or process component which has the following  (a) its manager reports to the entity's top management; (b) it is responsible for carrying out a mission, performing a line of activities or services, or producing one or a group of products; and (c) for financial reporting and cost management purposes, its resources and results of operations can be clearly distinguished, physically and operationally, from those of other segments of the entity.
Divisions are broken out into sectors depending on specific criteria.