How Millwriters on oil/gas Field are differ by work from welders ,pipe fabricators,hydraulic technicians etc?

For general information.How Millwriters on oil/gas Field are differ by work from welders ,pipe fabricators,hydraulic technicians etc?
A Millwright is basically a mechanic, using wrenches, pry bars, hammers. They install equipment, bolt down or remove covers from tanks, bolt up flanges and that sort of thing. It is often outdoors work and likely to be heavy work. If you are big enough to handle it that's a way to get into the oil/gas field. The work is hard but it pays pretty good and you will seldom be out of work.How Millwriters on oil/gas Field are differ by work from welders ,pipe fabricators,hydraulic technicians etc?
A Millwright can and will do any trade's work if given the chance. He is by design, a multi-craft trade. So, if you have a small crew in mind, millwrights are a good way to go. They also do construction of new factory's and power generation plants.