Circulator or pump?

You already have circulators, and will replace with another

A circulator is a specific type of pump designed for use in closed-loop systems, primarily for moving fluids like water in hydronic heating, cooling, or hot water recirculation systems.  While technically a pump, a circulator is specialized for low-pressure, high-flow applications where the primary goal is to maintain continuous fluid movement rather than to lift fluid against gravity or generate high pressure.  Unlike general-purpose pumps that may need to overcome significant static head (elevation changes), circulators operate within a pressurized system where the fluid is already at the required elevation, so they only need to overcome friction losses in the piping. this means that you already have Taco circulator pumps that circulate water in a closed system. All circulators are pumps, however, not all pumps are circulators. here are some pumps that do not circulate and can develop much higher pressure than a circulator:

As far as changing an existing circulator pump on your system, you are often better off replacing like for like as @GGross mentioned unless someone specified an incorrect circulator pump for your needs. This does not seem to be the case here. I have often found that you can purchase a new circulator pump of the same model number, and just replace the motor housing and impeller cartridge without needing to take the pump casing off of the connected piping. This saves time and labor hours.