Rugby Union, as represented by England Rugby Football Union at the professional level, suffers a concussion rate of between 3.9 [2] to 10.5 [3] per 1000 hours played. Therefore Rugby League would seem to have more concussions, however no major difference is definite given the limitations and bias of the data sources. read more
This study is quite interesting: Concussion in youth rugby union and rugby league: a systematic review. Here are some of the take-aways I got from this paper: Per 1,000 hours played, there were more concussions for youth players in League vs Union (incidence ranging from 0.2 to 6.9 concussions for rugby union and was 4.6 and 14.7 for League). read more
That’s not to say that rugby is necessarily safer. The sport’s chief medical officer Dr Martin Rafferty recently told the BBC that the rules may have to change to reduce concussions. The number of reported concussions in English rugby rose by 59 per cent in 2013-14. read more