When I was at school Sixth-Year Studies were supposed to be the equivalent of A-levels.
Though Highers are done over a year instead of two (or do A-level people do them in one year now?), and people doing A-levels usually do 3 instead of 5 for Highers so it probably balances out.
Personally I would have preferred to do 3 courses over 2 years instead of 5 over one year.