1 pass Vs 2 pass

Hi,

I have a question.

I understand that during rendering eg. 4000k is better that 2000k, and 6000k is better than 4000k, but what is option "2 pass" for?

Is "2000k 2pass" the same quality like "4000k", or maybe it something like "3000k"?

Forums:

Pass 1 does an analysis on where and when to best spend the bits during the second pass. It is difficult to compare # of passes to another bitrate level. Choose bitrate as needed for file size or bandwidth constraints. Do preview renders without multi-pass encoding. Then, do a final encoding as multi-pass if it is important or not if it is just something quick-n-dirty.