The answer to 'difference between SEER 16 and SEER 20' is that SEER 20 is a more energy-efficient air conditioning system compared to SEER 16. SEER, or Seasonal Energy Efficiency Ratio, is a measure of how efficiently an HVAC system cools your home. The higher the SEER rating, the more efficient the system is, meaning it uses less energy to cool your home.
Generally, a SEER 20 system will be more expensive upfront but will save you more on your energy bills over time compared to a SEER 16 system. SEER 20 systems are also often quieter, have better humidity control, and may last longer than lower SEER models. However, the actual savings and benefits will depend on your home's size, insulation, and other factors.