A person who drafts drawings using either a computer (CAD) or pencil, pen and paper. Modern drafter(s) use computers and drafting software (Cad monkey). Drafters usually work under the direction of a designer or engineer. Drafters are expected to be experts at creating drawings.
An engineer would like to present an idea. He would request a drafter to create a drawing.
One who has (through experience) acquired a complete understanding of designing piping systems. Pipers can be divided into two (2) classes: Contracts and directs. Real pipers are usually contractors, traveling from job to job seeking the highest current wages. Directs usually hang around after the contractors have left. They fix the mistakes, pick up the pieces, and pull the job together - usually at less wages.
This damn design is all f**ked up. Must have been one of them contract pipers.