It's in the implementation that the differences arise.
This is actually a great example of that. Helsinki makes sure that the housing sectors aren't segregated by economic class so that they have fully integrated communities. Every community has a mix of low income public housing, middle income and high income housing.
In the U.S., that was the original plan. Except here, private interests were able to successfully force all of the low income housing into limited geographic areas, which is what created the projects and ghettos. This matters because it impacts things like school funding, access to grocery stores, all sorts of little things that seem insignificant but directly impact quality of life. Additionally, if this had been implemented as intended, you couldn't create poor communities by just moving out of them because every community would be a mix.
If the U.S. had implemented their plan and stood up against private money, we would have had a different set of outcomes.
So, the difference between them and us is that they implemented the plan in the way that best serves the goal. We modify the plan in the way that best serves the biggest pockets. It's a very intriguing difference in implementation.