Difference between "a:active" and ".active a.class"

I have in a css file this:

#toolbar a.opener:hover,
#toolbar a.opener:active,
#toolbar a.opener:focus {
    something1;
}
#toolbar .active a.opener {
    something2;
}

Questions:

1. What is the difference between the "first active" and the "second active"?
2. When are called the "first active" and the "second active"?