Zoom in on Kinshasa though and you can see that it's almost entirely very densely-packed slums and shantytowns built up against each other, about 100 - 250 square meters in size, with no gardens or back yards. Slums can be very dense, Dharavi in Mumbai 2.3 square KM with a population of about a million. Manhattan has a much lower population density now than 100 years ago.

Also in all the street view pictures it looks absolutely packed - every road is gridlocked with people everywhere, but Shanghai has a lot of empty space for people despite its size. Roads have trees, they're much wider, there are a lot of open parks, office buildings etc that Kinshasa wouldn't have.