DBMS_JOBS vs DBMS_SCHEDULER

-> DBMS_SCHEDULER introduced in 10g releases so before this, we were able to use only DBMS_JOBS for scheduler jobs.

e.g. DBMS_JOBS
SQL>
VARIABLE job_id NUMBER;
BEGIN
  DBMS_JOB.submit (
    job       => :job_id,
    what      => 'BEGIN P_KILL_ALL_INACTIVE_SESSIONS; END;',
    next_date => SYSDATE,
    interval  => 'SYSDATE + 1 /* 1 Day */');
  COMMIT;
END;
/
PRINT job_id

e.g. DBMS_SCHEDULER
SQL>
BEGIN
  DBMS_SCHEDULER.create_job (
    job_name        => 'example_job',
    job_type        => 'PLSQL_BLOCK',
    job_action      => 'BEGIN P_KILL_ALL_INACTIVE_SESSIONS; END;',
    start_date      => SYSTIMESTAMP,
    repeat_interval => 'SYSTIMESTAMP + 1 /* 1 Day */');
END;
/

Ref for example: https://ozsoyler.blogspot.com.tr/2017/02/how-to-kill-all-inactive-sessions-with.html