There are no such things as cities in Oblivion (or Skyrim). Anyone saying otherwise is a moron, although the Oblivion towns are indeed much bigger than the idiotically small Megaton or Bigtown (which are even smaller than a single apartment block, I mean WTF).
You have to consider that these are scaled down from reality. A lot. Even in Medieval terms, the Oblivion cities are small villages, but they are supposed to be considered cities so that is how we must approach the view. If the cities in Skyrim are dramatically bigger, we can consider those towns in Skyrim's scale.
Now, as for towns/villages, I expect, if the 10+ houses for minor settlements report is true, to be generally between the size of Suran and Caldera in Morrowind. In a 15 building town, I'd probably expect 10 houses, a chapel, an inn, a blacksmith, a mill, and an alchemical shop, as a random example.