Thank you, pykälö, for your insights and clarification on the differences between "pienalueet" and "kaupunginosat." Understanding that "pienalueet" are statistical areas and "kaupunginosat" are used for zoning and planning is really helpful. This distinction certainly adds complexity to mapping efforts, especially when official and colloquial boundaries don't always align.

I would like to ask if there are any other sources where we could obtain accurate information on the names and boundaries of these areas? The Jyväskylä base map is one option, but it doesn't directly explain why some areas are labeled smaller than others. Is there any documentation or other information that clarifies these differences?

It would also be interesting to know how similar situations have been handled in other cities. Does anyone have experience or knowledge of how areas in cities like Helsinki or Tampere have been mapped in OpenStreetMap, and how differences between official and unofficial boundaries have been addressed there?