What's the difference between a delta migration and full migration?

A delta migration moves only those changes that were made to an environment after the last migration was done.

On the other hand, a full migration moves all changes made to an environment.

For instance, let's say Alpha is your source environment, and Beta is your target environment. You create object X in Alpha environment and do a migration. Then, you create object Y in Alpha environment and do another migration. If the second migration is a delta migration, only the object Y is moved. However, if it's a full migration, both the objects X and Y are moved.