Any device that is used to increase the temperature of the water depending by any means such as electricity, gas, or solar energy called water heaters. Then where did the term ‘Geyser’ come from?
In the real world, Geyser is a natural phenomenon where ground water gets heated naturally and water pumped with force. As this natural water heating, the process is called geysers, Geysers became synonyms for Water Heaters.
Next time when someone asks if there is a difference between geysers and a water heater, first get it clarified what they are talking about, is it natural geysers or domestic geysers.