Scale Models

Scale models are basically miniature copies of different types of objects. Here the copy may be smaller than the original but it will be sized to scale so that it resembles the original in every way. Scale models can be used in various ways from commercial purposes to collector's hobby items. Common uses for scale models include:

Commercial Scale Models

Here the model(s) will be used for commercial purposes. So, for example, they may be used in:

Architecture - here an architect may make a scale model of a building to show what it will look like and to help as a guide in the building process.
Engineering - here engineers may make scale models of products to test them out before they are developed in full.
Film - film makers will often use scale model sets to shoot certain types of scenes where it would be too costly or difficult to build a set to size.
Sales - sales people are often given scale model prototypes to use in the selling process to show customers.

Hobby Scale Models

Many people will make and/or collect scale models as a hobby. Common types of scale models here include:

Aircraft and Spacecraft
Animals
Cars and other vehicles
Die cast models
Dolls houses
Fantasy gaming models
Military battlefield models
Model railways
Remote controlled models
Ships (including ships in bottles)

In this instance, hobbyists making scale models themselves can either make their own models from scratch or they can make them up from kits.