Well, I am mechanical so an example of what we do is design and lay out, say, materials handling systems (conveyors, crushers, ship loaders, that sort of thing) whereas the structural guys have to design and layout all the steel work that supports out gear, and the civil guys lay out and design all the groundworks, drainage, sewerage etc and supporting concrete (that supports the steelwork that supports my crap) if that makes any sense
and then you have the electrical and instrument blokes, but no one likes to talk about them
PM replied too as well.