At the end of your driving test you will have been given a driving test report by the examiner called a DL25A, coloured green and it will have all your driving faults recorded.
A section on junctions is shown above as an example.
The driving examiner marks the errors on the report as they are committed. Where he/she puts the mark tells you if it was a minor error or a serious or dangerous error.
So in my example two minor errors are recorded for approach speed, along with one serious error on observations and one dangerous error for cutting corners. Notice the columns they are in. On your report sheet the two columns on the right are headed S and D for Serious and Dangerous.
Serious or Dangerous makes no difference to the result, just one of either will fail the test. However, you can have up to 15 minor errors before failing the test.
A serious is where your error might have caused an accident had there been someone there at the time, ie in my example you might have emerged from a junction without looking but there was no one there anyway; had there been someone there, an accident might have resulted.
A dangerous error is where your error actually caused someone to take action to avoid an accident; so in my example you might have cut the corner whilst there was someone approaching and they had to stop short or swerve to avoid a collision.
I have listed all the sections shown on your driving test report sheet. Look at your report sheet and click on any section for which you have an error recorded and a popup window will appear explaining the types of fault you might have committed; all faults are assessed at the time they are committed so what might be a minor in one instance might be a serious/dangerous in another; for example you might overshoot a right hand turn (what's called swan necking) and get a minor steering error (under controls) but if you mount the kerb the examiner will mark it as a serious error and if there was a pedestrian nearby who leaps out of the way you will get a dangerous error.