Ok, I admit it...
...I came here via HG after seeing the myriad trash posts there about BR. Then I downloaded BR and watched it.
It is, of course, outstanding. The best foreign film I've enjoyed since Cinema Paradiso.
It's also a completely different film to HG, which is a polished Hollywood big budget movie. BR gets straight to the point, and is relentlessly claustrophobic and dystopian, whereas HG is lush and ultimately concludes with the usual uplifting 'message' ending.
Most important of all, HG differs in that all the participants don't know each other, whereas BR is truly horrific because these are all classmates who grew up together. No-one identifies with HG's guilds, but we've all been in school and we all might imagine ourselves in the scenario as set out in BR. I thought the different strategies resorted two by the schoolchildren were very realistic - the ones who would commit suicide, the ones who would try and make peace, the ones who would seek vengeance for bullying - none of which was possible to develop in HG because the participants were pairs from different regions.
So I don't think there was plagiarism, and if there were then the plagiarist was an idiot to throw away the most poignant aspect - that they all grew up together as schoolchildren.
I enjoyed HG but it's forgettable. BR will leave me thinking about it for a long time...