Technologist/ Technician And Crafts Personnel

Technologist
A Professional Engineering Technologist is normally someone with an approved diploma in technical or software engineering or equivalent. His work is normally supportive to the engineer in such areas as computer aided design (CAD). This relieves the engineer of less demanding work. A Technologist uses scientific knowledge to solve practical problems.
Technician
The Engineering Technician is normally involved in practical engineering work and holds an approved engineering certificate or equivalent. Their work can be the repair of sophisticated equipment such as computers, printers, scanners, refrigerating equipment, televisions, instruments, telephone systems , and household appliances such as fridges , washing machines , cookers, CCTV, and even digital cameras, etc. They can also be involved in installation work such as the installation of burglar and fire alarm systems and the repair of same, to the installation and maintenance of gas installations, and commercial equipment such as that used in aircraft and in industry etc . There are many types of technician, installation technician , service technician , sound technician, engineering technician , accounting, computer, laboratory, medical, television, etc.
Mechanic
A mechanic is someone who uses his skills to repair vehicular appliances, aircraft engines and other machinery . In general, anything with moving parts. You have car mechanics, aircraft mechanics, instrument mechanics, etc.
Fitter
Fitters are normally associated with the repair of heavy machinery such as that used in industry. They install and repair gas boilers and systems. They also repair such equipment as fire extinguishers, air conditioning systems, escalators, passenger lifts, industrial boilers and systems, commercial refrigeration systems, heavy earth-moving equipment such as bulldozers, etc.
Plumber
A plumber is a person who fits and repairs pipes and fixtures for water, drainage, or gas, mainly in domestic premises. Plumbers also repair and install domestic and commercial central heating boilers and systems.
Electrician
In some countries electricians are licensed. Their work involves the installation and maintenance of anything that is powered by electricity. This can be domestic appliances such as fridges, cookers etc. Their work varies from the installation and maintenance of domestic and commercial equipment to the maintenance of very high voltage lines such as that in National Grids.
Artisan
An Artisan is a skilled person who makes things by hand.
Installer
An Installer is normally a person skilled in the practical aspects of installation work but limited in the theoretical aspect, e.g., Burglar and Fire Alarm Installer, Gas Installation Installers, etc. For complex installations you would have a commissioning technician. Servicing would then be carried out by a service technician.
There can be some overlap between some of the above categories of craft persons.