When you start up the game, there are only 6 neighborhoods. E001 is Belladonna Cove, F001 is Desiderata Valley, G001 is Riverblossom Hills, N001 is Pleasantview, N002 is Strangetown, and N003 is Veronaville. If you create a custom hood, it will become N004 by default, though you can change it if you do it correctly.
Any other neighborhoods that came with packs are subhoods and have to be generated. Along the top bar of the game, when you are in the neighborhood map, you can choose to create a downtown, shopping neighborhood, vacation neighborhoods, and University Neighborhoods. After you've generated them, they will appear within the neighborhood file for the neighborhood you generated them in. For example if you generate a University Neighborhood in Riverblossom Hills, you'll see G001_University001 for the first and then G001_University002 for a second one and so on. A Downtown subhood will appear as G001_Downtown001 for the first one. A vacation subhood will appear as G001_Vacation001 for the first one. As you play and generate the magic subhood by befriending a witch or hobby subhoods by building hobby enthusiasm, you'll start seeing G001_Suburb001 and _Suburb002 and so on as the game generates those subhoods.
