Germination and fusion happen to be two different phenomenal that occur in the dental field. Germination, however, refers to a state whereby a tooth extra is developed, while fusion refers to a state whereby a tooth is missing. These processes or phenomenal are usually common in children. In germination, the tooth of a child is split into two. It seems like there are two teeth growing from the same root.
On the other side of the coin, fusion is simply the state whereby two teeth are joining together to be one. It most likely seems like two different roots are producing one tooth. If you are not familiar with these phenomenal, you might find it difficult to differentiate between the two. However, a simple trick to it is that; count the teeth of your child. If it is increased by one, then it is germination. But if it reduces by one, then fusion has occurred.