When adding piping system to a Revit model, it is desirable to label piping systems with their system type so that you see text on the piping line. Some examples of this are HW for Hot Water, CW for Cold Water, and S for Sanitary Waste.
In AutoCAD, piping systems are typically shown by drawing a line with a specific line type that displays the desired text. This works fine since the lines themselves contain no data and are just symbolic. Revit does not allow line types with text in the line like is allowed in AutoCAD. However, Revit makes it super easy to label piping systems with the appropriate text. I believe that the net result is the same, if not better.
An important aspect of using Revit MEP is the ability to place pipes for various piping needs of a building project. When placing pipes, the user specifies the pipe size and elevation, but those have some caveats which may not be readily apparent or what the user assumes. There are pipe settings and parameters for diameter, nominal diameter, outside diameter, inside diameter, invert elevation, and justifications, which all interact with each other to determine the actual location of a pipe.
It can be a bit daunting understanding how the various pipe size parameters interact with elevation distances and dimensions. Hopefully, this article will help make it less daunting.