Literature summary: cooling capacity is a heat-removal rate, normally expressed in watts or kilowatts, with Btu/h or tons of refrigeration also common on U.S. equipment. Efficiency metrics compare output with input under defined test conditions; they are not interchangeable with capacity.
Rated performance depends on entering indoor and outdoor conditions, airflow, fan-power treatment, staging and the specified test method. A seasonal or integrated metric weights defined conditions and is not a promise of exact efficiency at every field condition.
Installed performance adds the building system: ducts, filters, coils, fans, dampers, controls, ventilation and heat rejection. A correctly rated unit can still miss the occupied result when distribution or controls are wrong, while oversizing can create cycling and moisture-control problems.
Useful comparison begins with the actual load profile and acceptance target. Larger nominal capacity can increase first cost and change part-load operation; higher rated efficiency does not repair excess load, inadequate airflow or an incorrect sequence.