I guess that you have not played this trick before.
Google Space was adopted from Angry Birds Space game. When Angry Birds Space got released on March 22, 2012, Mr. Doob as the author of this trick thought that he should also make a space mode to Google Gravity.
Unlike other tricks, this trick couldn’t be played by clicking “I’m feeling lucky” button.
To play Google Space trick, you can directly go to this link.
Technically, Google Space is the same simulation with Google Gravity but without the gravity component. The experience, however, is a bit different. If in Google Gravity all components of Google page are falling down due to the influence of gravity, then in Google Space all components of Google will be hovering like in outer space that has no gravity.
Another difference appears when you do searching. The search results will suddenly appear out of nowhere unlike Google Gravity that fall down the search results from the top of the page.
The rest I think there is no difference between the two. And the conclusion is you must play Google Space.