I'm afraid that I'm not yet sure how Google Chrome really differs from Chromium in Linux, specifically in Ubuntu. This site shows the differences between both variants. However, it seems that that table is not quite reliable. It says, e.g., that for Adobe flash Chrome has its "custom (non-free) plugin included in release". But if I uninstall the adobe-flashplugin package, flash in Chrome doesn't work - it obviously doesn't have its own plugin included. It has its own PDF viewer, though. The sandbox is, as the table says for Ubuntu, enabled in both according to chrome://sandbox. One difference which I found: In chrome://flash Chromium has the warning: "GPU access is not allowed" while Chrome doesn't show that. Can someone with more knowledge about Chrome/Chromium enlighten me?