Why does Date.parse give incorrect results?

Case One:

new Date(Date.parse("Jul 8, 2005"));

Output:

Fri Jul 08 2005 00:00:00 GMT-0700 (PST)

Case Two:

new Date(Date.parse("2005-07-08"));

Output:

Thu Jul 07 2005 17:00:00 GMT-0700 (PST)

Why is the second parse incorrect?