Compressor Performance Differences. We’re talking about compressor types: Basic: A single-stage compressor always operates at 100% capacity Better: A two-stage compressor has a low capacity, which is about 70% in most models, and high capacity (100%) Best: Variable-capacity (also variable-speed and modulating) compressors vary capacity from about 40% to 100% in increments of less than 1%.
https://www.pickhvac.com/faq/singal-stage-vs-two-stage-for-heat-pumpac/

