I have a question. will the search results be different if using google.com in different countries? of course in the case of searching the same english keywords.
Normally you will get a unique result from the server where we request for any query and also it is time dependant.If 2 consecutive searches happen same time there may be some difference based on location
As of a couple of months ago, Google have started personalising everyone's results even if you are not logged in. Google for "Google Now Personalizes Everyone’s Search Results" (I can't do links yet, hope it is okay for me to say "Google for...") So now you can't be sure what anyone will ever see.
the sponsored search results will also be different because advertisers can target specific countries. So I might advertise my product in Europe and in America it won't come up in the results
In my own experience I got the same results through different sites but if there are some geo-targeted based on my query, I got several different and that includes normal listing and sponsored ads.
Absolutely, you WILL see different results from different IPs/geographic areas. If you deliver products overseas, be sure to check international Google urls. I wonder if site:domain.com gives different results too???