The answer is, usually they do but not in all situations. So let me give you a couple of situations where it could differ. If you um, you know, personalization is based on who we think you are. So if you’re logged in versus not logged in that might make a difference. Maybe you’re logged in on one browser and you’re not logged in on the other.
Another thing that might make a difference is sometimes different browsers support different functionality. So even though the search results didn’t change, last year we were using AJAX to sort of return very fast search results on Firefox and Internet Explorer didn’t really have the support for that, that we would like. So Internet Explorer eventually got that support but for a while if you searched on Firefox you’d get the results in sort of this fast AJAX form, whereas internet Explorer would do the conventional sort of way that we would return search results. That typically wouldn’t vary the search results, but in theory it’s possible.
The last thing would be if you might be in what we call Bucket Testing. Now that sounds really unflattering you know. Where’s my bucket? What’s this bucket doing on my head? So think of it like Cookie testing. Different browsers depending on when you visit Google might get different cookies, especially if you didn’t log in.
It can be a large absolute number, amounts of tests on users as they’re using Google. So for example we just rolled out a new way of presenting our search results pages. Whenever you were using Google you might have gotten into this Cookie test or Bucket test to see those new search results.
So depending on which browser you’re hitting, whether you’re logged in or not, which cookies you have, all that sort of stuff, you might get slightly different testing done on the search results. And that could include different algorithms. So while the vast majority of the time when you’re doing a search on Firefox, Internet Explorer, or my personal favorite which is Chrome, you’ll get the same search results, it is possible to have different search results between different browsers.
by Matt Cutts - Google's Head of Search Quality Team