from my Aerospace days we had :-
Engineers, degree qualified, designed and specified equipment such as test equipment and parts of planes and missiles
Tech Eng - worked closely with the above to build working prototypes. Generally HNC, time served apprentices, main role was to take the designs of the above and make it work, which often involved a bit of re-design, drawings, all sorts. Often responsible for writing manuals and passing info on to shop floor staff and technicians. Quite often sent out to service equipment 'in the field'. Often left to design and build test equipment of the simpler variety.
Technician - trained to work with whatever the above 2 categories came up with as a working product, usually ONC and time served.
Cross over between roles was not unusual if the candidate had the right skills or knowledge.
In my opinion the better Electricans and plumbers of the world are at Tech Eng level. The worst don't make Technician. Being the Aerospace industry, it was an essential requirement that Engineers were Degree qualified minimum in an appropriate technical discipline.