Static.

You populate a static deployment group by manually selecting objects. Create a static deployment group if you do not expect the set of deployment objects to change. For example, you might group objects for deployment on a certain date and deploy all objects at once.

Dynamic

. You use the result set from an object query to populate the deployment group. Create a dynamic deployment group if you expect the set of deployment objects to change frequently. For example, you can use a dynamic deployment group if you develop multiple objects to deploy on different schedules. You can run the dynamic deployment group query multiple times and add new objects to the group each time you run the query.