While all plumbers may seem the same, there can be a major difference depending on their area of specialisation. For example, a residential plumbing expert usually performs the same tasks, which are normally related to blockages, leaks or water heater problems.

A plumber can undertake work in both commercial or residential sites, but some plumbers choose to specialise in one or the other. Residential plumbers are experienced with problems and repairs for systems that are relatively smaller in scale. Commercial plumbers, in contrast, may have an understanding of larger systems.

Commercial plumbing specialists tend to focus on maintenance work rather than problems, as commercial property owners tend to be more concerned about preventative maintenance when it comes to the plumbing system.

They are more likely to visit locations on a regular basis to check for potential problems. They are also more likely to undertake after-hours work, due to the types of buildings and sites they service.

Source:http://plumbinghelptoday.com/denver-plumbing-repair-blog/2013/07/the-difference-between-commercial-plumbing-and-residential-plumbing/