what is the difference between DataSet.Copy and Dataset.Clone methods?

1. First one copies all tables of Dataset but second one copies some portion of the Dataset

2. First one copies tables of dataset defined by the user , second one gives memory size of the dataset

3. first one copies both data and structure of the table , but second one copies only structure of the table

4. first copies only structure of the table but second one gives memory size

5. None