hrp's are a close cousin of cons .... more colorful fins and supposidly a little less aggression... but I wouldnt want to put it to the test with a pair in a community setting...
They are different species. As lp said, the HRP's have more blue, and I think some more reddish coloration, especially in the tail - correct me if I'm wrong.
They are indeed a little less aggressive than convicts, but it depends on what fish you are keeping already.
Typically cons are gray or pink, with a more pointed nose. HRPs on the other hand are typically very blue, with a more rounded nose. Generally they're considered to be milder than cons, but when breeding they are equally as aggressive as cons tend to be...
Take my male HRP brutus for example...
And my last con as an example (though he was not a typical con in that he had a much bulkier body)
at the store
But yeah, my male HRP brutus is the boss of my 9.5" oscar, so I think that says it all about their personalities.