It really is misleading to call any auto battery sealed. If it were truly sealed it couldn't function as an auto battery.
That being said, what is different about a "sealed" auto battery is the necessary vent hole required for the sensor to function is moved to the side, somewhere near the
threads. Instead of being located right in the center of the positive post on the battery. The side placement of the vent hole makes it less likely you will get liquid into the battery during a leaking accident. But it doesn't make the battery truly leak proof nor sealed against a major flooding accident. A healthy amount of paranoia is still required to minimize any risks to the battery from flooding.
