Neither place is planned. They build according yo their conditions and the anarchy of capitalist production.
In Nuuk land is cheap and there are not many people. They build Nordic style things imported from Denmark etc. They are decent for retaining heat and withstanding snow and are made from mass-produced parts.
In Rio there is a wide diversity of density, but in short, lots of people live there. They build with thr materiaps they have. Large dense buildings there are semi-planned as large real estate ventures. Their goal is to make money, primarily a form or monopoly rent via geographical constraints. The bankers living near work, the financial companies working near each other, etc.