Well, this is probably a bit silly question but I just need to know. What is the difference between a boiler and a water heater. I see both terms used and it looks like they are two different things. So I just want to know. What is a boiler and what and what is a waterheater

lots of folks use "boiler" for any big apparatus that heats water. However, a boiler is not a water heater, nor vice-versa. Using the terms interchangeably in incorrect.

So what is a water heater? It is a tank in which water is both heated and stored, and that last word is probably the key difference, since some water heaters approach boilers in their ability to heat water.

A boiler is essentially a box, often full of copper tubing, through which water flows to be heated very rapidly. A boiler can heat a whole complex, or a pool, or a hot tub. It also requires controls and pumps that are more complex than those for water heaters.

Very high recovery water heaters can do these things, too, but they have so many flues inside to transfer heat that they begin to resemble boilers.

There are always exceptions to the above. Some people have fashioned storage tanks to a boiler system but the above is a general guideline acknowledging there are always exceptions.