What is fertility of soil and what is the difference between aforestation and reforestation?

Fertility of soil is the condition when soil has appropriate amounts of minerals, nutrients, aeration and water holding capacity to sustain life on it like grow crops, plants trees etc. Fertile soil usually contains organic matter that improves soil structure and soil moisture retention. It also hosts a range of microorganisms that support plant growth.

When trees are re-planted on areas that were initially covered with forests, it is called Reforestation while when trees are planted on areas that were initially not covered with forests but are plain areas, it is called afforestation.