Generally there are two types of plumbing layouts found in homes, series plumbed and branched, with various combinations. We will first examine a typical series plumbed system. I have simplified the illustrations showing only the water heater and sink type fixtures, leaving out showers, bath tubs, etc. A series plumbed system means that the water lines go from one fixture to the next, then from that fixture to the next, etc. This is typically the way the piping is plumbed when a hot water circulating system is going to be installed.
Branched systems are far more common.
When a new home is being built, there is no diagram in the blue prints showing how to layout the plumbing system. The fixtures are shown, but how the piping gets to and from the fixtures is up to the plumber. Thus even with identical floor plans there can be a number of variations in how the piping is laid out. Two typical branched systems are illustrated below.