Plumbing is any system that conveys fluids for a wide range of applications. Plumbing uses pipes, valves, plumbing fixtures, tanks, and other apparatuses to convey fluids. Boilermakers and pipefitters are not plumbers although they work with piping as part of their trade and their work can include some plumbing.
A water heater is a storage tank that, yes, heats water. We depend on Rheem and Bradford White to deliver a quality product.
Soldering is a very reliable and great way to plumb, but it is not the only way.
Did you know your home plumbing system makes up about 15 percent of your total home value? That's an important investment. It might be smart to learn when to call the plumber.