Shallow clone: only duplicates the metadata of the table being cloned; the data files of the table itself are not copied. These clones are cheaper to create but are not self-contained and depend on the source from which they were cloned as the source of data. If the files in the source that the clone depends on are removed, for example with VACUUM, a shallow clone may become unusable. Therefore, shallow clones are typically used for short-lived use cases such as testing and experimentation.
Deep clone: A deep clone makes a full copy of the metadata and data files of the table being cloned. In that sense it is similar in functionality to copying with a CTAS command- but it is simpler to specify
