When you use the auto-catalog feature you can import an entire PDS and all of its members, whereas a regular import only supports the import of individual PDS members.
Example:
MFDAS IMPORT c:\mfi01.test.cobol\ FROM PDS mfi01.test.cobol /CATLOC=c:\proj\catalog.dat
Executing this command results in the following files being imported:
The IMPORT command creates the folder mfi01.test.cobol\ if it does not already exist, adds a catalog entry for the PDS, then imports and catalogs the PDS members into that folder.