container clause vs container_data clause in 12cR2

Hi,

Anyone know the difference between container clause and container_data clause in 12cR2

sqlplus system@CDB1   (root)

ALTER USER c##admin1

SET CONTAINER_DATA = (CDB$ROOT,PDB1)

CONTAINER=CURRENT;

how would it be different if I said below, and why should we even need this

CONTAINER=ALL;

According to documentation for release 2,  "To specify the container_data_clause, the current session must be the root and you must specify CONTAINER = CURRENT."

It's same in release1

https://docs.oracle.com/en/database/oracle/oracle-database/12.2/sqlrf/ALTER-USER.html#GUID-9FCD038D-8193-4241-85CD-2F472…