They are inter-related terms depending on which part of the world you are in.

https://www.houzz.com/magazine/interview-whats-up-with-prefab-stsetivw-vs~429292

https://www.houzz.com/magazine/houzz-tour-a-new-look-for-prefab-tailored-by-local-craftspeople-stsetivw-vs~27438625

Like Dytect said, this is one of those areas that the term "prefab homes" has become the catch all term used for everything from modular prefabricated homes (ready to live in once moved to a site) to kit packages (precut components assembled on site) to true panelized components fabricated in controlled environments that are then assembled together on site, to everything in between.

And yes..... prefab homes have come a long way from those early years. Be it completely finished modular units, to kits, to panelized components. The key to any construction, be it stick built on site or prefabricated in a controlled environment, is the company doing the work and their attention to details and commitment to quality.

Do your due diligence if you're interested in this possibility and the best place to start with is your local code authority and permitting department. Find out what they will accept and what their acceptable range is for "prefab" and what their understanding is of the term and the concepts............you would be surprised. I know someone who thought they had covered their bases, only to be told on the site once the panels were delivered for assembly, that they were not acceptable..........the inspector thought "prefabricated panels" were something like a "modular home"......?????

After several months of explaining to the local code authority, supporting documents signed and sealed by structural, electrical, and plumbing engineers as to the code compliance designs and concepts..........the owner finally had to appear before the County Commissioners for a variance before they were allowed to continue.

i would love to work with you man.

there is so much more i would love to learn about building houses.