Names on packages often are defined by the mfg. marketing department. They are only concerned with boosting sales.
Double check function after you buy. Get a cheap digital volt meter at your local hardware store. Install the maintainer device. Periodically measure the terminal voltage until you know it is stabilized. Also monitor water level until you know how much will be consumed.
Stable terminal voltage must be above 12.7 volts for storing lead acid batteries. Lower than that will shorten life (decrease capacity).
13.2 volts is ideal. It will consume minimal water and not produce significant heat. Long life is assured.
13.6 volts is high for AGM sealed batteries. Don't go above this for AGM's.
14.4 is not ideal, but is OK for flooded cells. It will consume large amounts of water. It is very bad for AGM batteries. Some maintainers spike 14.4 volts periodically for conditioning flooded cell batteries.
15 volts is too high for storage. Don't do it.
Your built in converter/charger/inverter may do an excellent job of maintaining your battery banks. Do the same voltage measuring to evaluate it.
I wish you good luck and happy trails ahead!