More specific, well then. Imagine I have 2 maps. 1 of these maps is the map of a country (let's say US). Now I need to put on this map the map of a state, let's say texas. The 2 maps have different size. I need to put texas in the correct position on US map, and in the correct size. In illustrator I normally put one vertex of texas on the same vertex on US map. Then I use the resize tool, and I put the center of resize on that particular vertex. then, I stretch the shape of texas until I hit a second point which should coincide. If the process is correct, the 2 shapes will match perfectly.
If I am not clear enough, let me know, I'll take some screenshots.