Difference between SYSDBA Privileges and SYSOPER Privileges

Sysdba Privileges vs. Sysoper Privileges

Hello everyone,

Why SYSOPER has limited session privilege?

SQL> show user;
USER is "SYS"

SQL> select count(*) from session_privs;
COUNT(*)
----------
166

SQL> conn /as sysoper
Connected.

SQL> select count(*) from session_privs;
COUNT(*)
--------
  3

SQL> show user;
USER is "PUBLIC"

SQL> select * from session_privs;
PRIVILEGE
----------------------------------------
CREATE SESSION
RESTRICTED SESSION
SYSOPER
SQL> conn /as sysdba
Connected.

SQL> grant dba to rs;
Grant succeeded.

SQL> conn rose/rs
Connected.

SQL> select count(*) From session_privs;
  COUNT(*)
----------
       161

    SYSDBA PRIVILEGE having session privilege: 166
    SYSOPER PRIVILEGE having session privilege: 03
    rs (normal dba ROLE) having session privilege: 161

Please clarify - where I am unable to understand about privileges?

Thanks.