What's the difference between tank and tankless water heaters?

Answer from Blake Grambusch

Okay. What is the difference between a tank and a tankless water heater? Uh, first off, the obvious. One has a tank and one does not. The way they work is a tank water heater holds and stores hot water and continues to reheat the water as the temperature goes lower. A tankless will heat water on demand. So, it only heats up the water if it's if you're using a fixture with hot water, it'll instantly heat up the water as hot as it really hot and get the water over there on demand. So, the difference is is if you want to use more energy at one time to heat up the water or use low energy and keep it hot and store it somewhere. Those are pretty much the two big differences.

Summary - TLDR

blake grambusch outlined the primary difference between tank and tankless water heaters: tank heaters store and reheat hot water, while tankless heaters heat water on demand. They explained that the choice depends on whether one prefers to use more energy at once to heat water or use low energy to keep water hot and stored