We have 2 teenage dc and I think costs now are probably the same as when they were pre-school. When they were little my (part time) salary was exactly the same as the childminding costs. I now work full time and about half my salary goes directly on their costs.
I pay £200 pm for their allowances, about £100 for their school lunches (they take packed lunch most if the time), £200 for driving lessons for dc1 plus £80 for insurance. £80 for dc 2 music lessons, plus £20 for sport subscription. We live in a very rural area so the driving is almost obligatory.
Obviously things like school trips are optional, and we have avoided the most expensive ones, but we paid out over £1k last year for 3 school trips.
We take them to visit their grandparents who live abroad, and they are adults on the plane so that is £ 3600 for 4 plane tickets because we have to go in school holidays. When they were preschool we used to go for about half of that because we would go at a cheaper time. I appreciate most people don't have family abroad though.
On top of that there is the cost of the food, they can eat through serios amounts of cereal and bread.
If I think about it though, the biggest cost of all is that when they were small we outgrew the house we were in and moved to a larger one, adding £100k to our mortgage.
Both dc are likely to go to uni, so that will be several thousand a year per child even if they get maximum loans etc.
I think if you are already in a large enough house, avoid things like school trips or holidays, and are paying large childcare bills, then the cost is the same. If you have to factor in moving house or if your children go to uni then they are definitely more expensive.