Final answer:
The government structure characterized by specific tasks allocated to distinct groups and represented by a pyramid is called bureaucracy. It operates on hierarchy, specialization, and formal rules, unlike an oligarchy where a small elite holds power.
Step-by-step explanation:
The structure of government designed to give specific tasks to specific groups or individuals, which is often symbolized by a pyramid indicating more individuals at the lower levels with less power and a lesser number of individuals at the top with more power, is called bureaucracy. Unlike an oligarchy where power is held by a small elite group that may ascend due to wealth, military might, or economic power, a bureaucracy operates on the principles of hierarchical authority, job specialization, and formalized rules. This system is essential in managing large political units efficiently, despite being prone to certain inefficiencies such as waste and rigidity.
Bureaucracy is not only unique to government but also found in private and nonprofit sectors, playing a pivotal role in managing tasks of significant complexity and magnitude.