Understanding Scale
When hobbyists speak in terms of "scale," they mean how large an item is as related to the size it would be in the real world. If the scale is "1:100," then a model 1 foot long represents something 100 feet long.
HO scale
HO trains, figures and other models are 1:87 scale. The name "HO" comes from the fact that it is roughly half the size of O scale ("zero" scale).
N scale
N scale models are 1:160 actual size. "N" means "neun," the German word for "nine," reflecting the fact that the track's rails are 9mm apart.
Appeal
Being larger, HO models are easier to handle and to see. N scale is appealing to model railroad enthusiasts who enjoy building detailed sets that use less space.
Your Own Railroad
Merchandise in HO and N scale is widely available in hobby and craft stores. Some items, such as artificial plants and rocks, work well with all scales.