“audit create session by session” vs. “audit create session by access”?

Question

When I enabling auditing for create session by the following way:

audit create session by session;

Then I am querying the following:

select * from dba_priv_audit_opts;

The result is:

USERNAME | PROXY_NAME | AUDIT_OPTION   | SUCCESS   | FAILURE  |
...............................................................
 -       | -          | CREATE SESSION | BY ACCESS | BY ACCESS|

But, when I enabling auditing for create session by the following way:

 audit create session by access;

Then I am querying the following:

select * from dba_priv_audit_opts;

The result is the same:

USERNAME | PROXY_NAME | AUDIT_OPTION   | SUCCESS   | FAILURE  |
...............................................................
 -       | -          | CREATE SESSION | BY ACCESS | BY ACCESS|

Why? Do you have any idea?