A model name tells you which product line a unit belongs to. It does not tell you how the unit will run in your house. The spec sheet does. Read the ratings and the install notes before you compare two heat pumps, because the same name can cover different configurations.
Find the rating block
Most spec sheets list cooling capacity, heating capacity, a seasonal efficiency rating for each mode, a sound level, the refrigerant type, airflow, and electrical requirements. Write each one down for both units. A missing line is a question to ask, not a blank to skip.
Ask which system the rating covers
A rating is tied to a specific combination of outdoor unit and indoor coil or air handler. Ask whether the figure is for a matched system or a mixed one. If the rating assumes a coil you are not buying, that number does not describe your house.
Check the cold weather limits
Every heat pump lists a lowest outdoor temperature at which it can run on compressor heat alone. Ask what provides heat below that line, and whether a backup heat source is in the scope and the written cost. In colder climates this is the line that decides how much of the winter the unit can carry by itself.
Confirm the electrical and install notes
Read the electrical block for the circuit requirement, the disconnect, and the minimum clearances around the outdoor unit. Ask whether the spec calls for any change to the electrical service, and get that answer in writing from the installer. Clearance and pad notes belong in your site check before anyone orders the unit.
Compare on the same basis
Put the two sheets side by side. Check that both use the same rating conditions, the same units, and the same listed system. If one sheet gives a figure the other leaves out, ask the seller for the missing figure before you decide between them. For planning dates, the heat pump service life and when to plan page on this site turns an install year into a planning window.