Actually it`s all about the ruler and the people
In the Ultramar Empire life`s good, really good. So you can expect to see a green park every now and then and other such humane things.
But it`s all up to the Chapter, I`ll take you back in time, prior to the heresy. Nightlord`s homeworld was a horrible place to life either because of the scum that infested the streets or the terrible batman-gone-crazy cleaning it up
But you could expect most SM homeworlds to be a generally better place to live then most imperial world. On one hand, corruption shouldn`t be abundent and on the other hand the inquisition`s forces would be almost non existent
But i`m pretty sure most use hive cities, even though i never saw a complete description of what they are
so for now to me their just realy big and really crowded and clustered cities