Why are Google Webmaster Tools' Google rankings different to actual Google rankings?

[BoomDialogue69]

Dear Moz,

We have noticed that according to Google Webmaster Tools one of our client sites is ranking very prominently for some of the major key phrases that we are trying to rank them for.

However, when we perform a Google search for these queries, our client's content is nowhere to be seen, not even on the 5th page (we logged out of the Google account before performing the test).

A long-term manual spam action on our client's site was recently lifted by Google - is it possible that Google Webmaster Tools is providing data about our client's estimated Google rankings, without taking into consideration the penalty of the manual spam action which was taken?

Thanks

[CleverPhD]

Do a search on Google search personalization.  Example

http://en.wikipedia.org/wiki/Google_Personalized_Search

What you see when you search is based on if you are logged in (or not), your IP, your previous searches etc.  These days there is no single ranking level, you are seeing a sort of average.  Rankings are more useful as a relative measure vs an absolute.  Are you moving up or down, is that causing increased or decreased traffic and is that traffic converting at a higher or lower percentage level.  You really need to look at all of that together and use ranking as a way to diagnose any issues with your final conversion numbers.

[BoomDialogue69]

Hi and thanks for your response.

I'm not sure Google Webmaster Tools takes into consideration a person's IP address when they list Google rankings for a website in Google Webmaster Tools. These rankings are linked to Google Analytics for a client website.