Basically, you have a free choice at which school type you want to register your child. Pupils aged 16-18 should seek advice on which type of school is suitable for them. The state school boards (https://www.schulministerium.nrw.de/docs/bp/Ministerium/Geschaeftsbereich/Staatliche-Schulaemter/Adressen-Schulaemter/index.html) help with consultation.