Yeah I know the difference very well. RBP are honestly some of the biggest wusses when it comes to piranha species. Hell even exodons are more aggressive then a RBP, but I've still seen convicts beat the living $heet out of fish 20-30x their own size with no mercy. I've seen my lfs add convicts in with black diamond rhoms and just end up with a dead rhom within an hour. All just because the rhom has no way of fighting back against a couple of fish a fraction of its own size, especially when the convicts double team it. Kind of hard to fight something that can move faster then you can, is more agile then you and has numbers on its side. Granted it's a bit different when it's just 1 fish against 1 fish, eventually the convict would be grabbed by the rhom but I doubt that would do much to stop the convict from continuing the assault unless he killed/crippled it in that 1 bite.
Ik the same lfs had one of my lil baby flowerhorns, it was the last one left over that they hadn't sold yet, in with a few big RBP's and they did nothing to her, and yes the FH did get sold at some point, but even I was surprised that a lil 3in FH ruled a 200g tank with 3, 9in RBP's in it. She had em all piled into one corner the entire time she was in with em. I would've figured they would've eaten her but nope she was the boss of that whole tank. Someone else bought the RBP's shortly after they sold the FH.