The answer to 'difference between replacement and' is that replacement and repair are two distinct approaches to addressing issues with your HVAC system. Replacement involves completely swapping out an old or malfunctioning unit for a new one, while repair focuses on fixing specific problems with the existing system.
Replacement is typically recommended when the HVAC unit is nearing the end of its lifespan (around 10-15 years for most systems), or when the cost of repairs becomes too high compared to the value of the old unit. Replacement provides the benefit of a brand-new, energy-efficient system that can improve your home's comfort and reduce energy bills. However, the upfront cost of replacement is generally higher than repairs.