Previously, the universities in Scotland were geared towards teaching straight after Highers, which you sit one year after NAT 5s (GCSE Equivalent exams), so the honours courses lasted 4 years. I went to university one month after I turned 17, but would have still graduated at the same point as an English student because they do 2 years after GCSE and then 3 at university.
So 1+4, versus 2+3.
However, the Scottish system is more flexible, because if you don't get sufficient points in your Highers, or you just weren't ready to leave home, then you could stay on another year at school and either do more Highers or take something called Advanced Highers (which were called sixth year studies in my day).
TBH the 3 differences are: Reception (what is the point of that?!), more flexible starting points in Scotland and we don't have sixth form colleges. The last year or two are just another school year. We still wore uniform and we were still called "pupils" until we left school and went to university.