There is a huge difference. Why would someone who only does domestic need to know about 3 Ph, Motors, VFD's, design outside of standard circuits, control panels and systems, PLC ' S, HVAC, refrigeration to name a few.
Also, to fault find on single phase domestic circuits genuinely is is easier. Heating controls being the most complicated they are likely to encounter.
There seems to be a lot of biting at people on here who are only wanting to do domestic saying they need to be more qualified. I think the Domestic Installer qual is adequate and a sensible and conscientious guy can do a good job and work safely. There are horrendous fully qualified sparks out there on industrial / commercial for sure so fully qualified is no guarantee.
Prepared to have my head blown off!!...... Lol