Ge Water Heater Features

If I get a water heater from a plumber or from Home Depot, how do I compare them?
If I buy a Rheem/GE water heater at Home Depot, I can compare a bunch of different water heaters there, and choose which one I like best according to its features, such as how fast it heats the water, how good its warranty is, etc. But if I buy a water heater from a plumber, I just get a total cost including installation, and no information at all about what water heater I’m getting. Even if the plumber gives me the model number of the one he plans to install, it’s different than the model numbers at Home Depot. For example, some of the model numbers at Home Depot start with 42V but the ones from the plumber seem to start with 82V. Are 42V and 82V equivalent, or is 82V old, or what?
Oops. The 82V is electric vs gas. That’s why I couldn’t find it. The plumber made a mistake when he gave me the brand and model.
A good plumber should be able to give you the years of warranty…the btu recovery rate name/size and all.
The brand name should have a web sight and his model number should be in their info. Match the warrenty years and the BTU recovery rate. IE..
A 40 gallon heater with a 12 year warranty and a 37,000 BTU recovery.