In some turbulence conditions, the gust suppression is working but not able to so call 'predict' what's ahead. therefore,minor over corrections or under corrections. Thus results in many minor lateral 'jolts'. This is a character of the B777. In the A330, it fish tail. Imagine pin the cockpit on a dart board and let the tail sway. The A330 tail will oscillate in a 'U' shape manner. Making many first time travellers at the back end feel sick.....crew too.
Not here to judge which a/c is better. They are build definitely less tough than the B747 but that dinosaur burns nearly 5000kgs more per hour.