"N"ew to "N" scale

[Sumpter250]

An SD90 in N is as long ,but not as high or wide as an F unit in HO. An 85 foot auto-rack car is as long but not as high or wide as a 40 foot HO box car.

a N&W 2-8-8-2 with its tender, in N, is as long ,but not as high or wide as an HO 60' boxcar You can have a "long" train in N at 10 feet , with a lot of hoppers, loaded with coal, and not have to double head the power. OR: you can model a shortline railroad, with a 2-8-0, or most any of the Geeps, with a small enough consist that still looks good in the space of your layout.
Aside from the amount of layout, with respect to available space, there's not a lot of difference planning in any scale. I, personally, tend to make the layout, and its features, fit the kind of power I want to use on the railroad that inhabits that layout.......or did, until I went to modular. Then, it became more about the "scene", as the "layout" depends on who is bringing what modules to connect and run on.
In the case of my Ntrak module, the scene is based on the concept of my railroad's "owner" / parent company, a shipyard.