An engineer examines problems and works out (engineers) solutions.
A technician applies pre-designed technical solutions to situations.
A fitter takes stuff out of a box and places it in its intended location.
An electrical engineer will measure an installation, calculate requirements, use those calculations to work out appropriate installation designs. (This is a second floor flat, the supply is 60m away, the voltage drop will be... the cable will need to be....)
An electrical technician will take pre-designed standard design solutions and apply them. (Two storey house, 2.5mm T+E ring main, 1.5mm lighting spurs)
An electrial fitter will take an item out of a box, follow pre-designed instructions, and attach it. (Remove old light switch, wire up new light switch)