There are four kinds of fault : (1) not worthy to record; (2) driving fault ("minor"); (3) serious ("major"); (4) dangerous (also "major"). They're defined here. Get 1 or more major or more than 15 minor, and you don't pass. (See common test faults, and when learning).
FAULTS NOT WORTH MARKING usually concern technique. Like "dry steering", crossing hands, not using handbrake button, selecting gears you don't then use. (These are matters of finesse).
DRIVING FAULTS may be potentially dangerous. Like not checking it was safe to signal. Making the same error a number of times shows a weakness likely to lead to danger. (Here's what to do if they happen).
SERIOUS FAULTS are potentially dangerous. Like failing to look properly.
DANGEROUS FAULTS involve actual danger (to you, other people, or property). Like going when there wasn't safe space. To avoid collision, the examiner either brakes/steers or tells you what must do.