Over here in Belgium it's like this: Kindergarten (2,5-6) (not obligated), primary school (6-12), high school (12-18) and after that it's university (academic or professional, usually 3 to 5 years). We also have something like a 'specialisation year' after high school, but it's for those who won't go to college and start to work right after that (for example: a plummer).
Our high schools are divided in 4 parts: ASO, TSO, KSO and BSO.
*ASO=you are being prepared for college. From the beginning, you can choose a course which suits you best (I chose Latin-modern laguages, you can also choose science-mathematics, economics-modern laguages, etc. Whatever suits you best!)
*TSO=more technical, rather a preparation for work (You have subjects like accountancy, languages, maths, etc. These subjects are more work-orientated then those you get at an ASO-course). You can also choose from the beginning what suit you best.
*KSO=art school
*BSO=you learn for a profession, has a seventh year for specialisation
Each part provides basic education, like history, maths, etc. In each part you can choose a course, which allows you to specialize in your favorite subjects. The difficulty of the subjects depends on the part you are in. For example: the subject 'French' in ASO is taught at a higher level than in TSO.
For example: I chose for the course Latin-Modern laguages (I had subjects like Latin, French, German, English, Spanish, Dutch, history, physics
, maths, etc.), which falls under ASO, because I was good in languages and I love to write. It also helps me now at university, where I study journalism.
Over here you can't leave school at 16. You have to stay till you're 18.