CompetitiveComparing your results to a competitor. For example, a transport company might benchmark the energy efficiency of a fleet against a close competitor.
FunctionalComparing your results to a firm or industry with which you don't directly compete. This is often done to compare your results to best in class processes and practices. For example, an airline might compare their customer service metrics to a luxury hotel as opposed to other airlines.
GenericFoundational metrics such as revenue per employee or return on investment that provide a common basis of comparison independent of industry.
InternalIt is common to benchmark things internally to measure improvements or to create a sense of internal competition.
Comparing results with standardized measurements.