I'll have a go at a reply seeing as no one else has, but I have no knowlege of the groups beyond being a customer myself.
I'm pretty sure they are just slightly different skins of the same casino. I know that casino rewards, belle rock and vegas lounge state that a welcome bonus cannot be claimed again at a partner casino within their groups. If you contact CS, they can serve you on any issue involving any of the family of casinos and they have access to all history. Some partner sites (ie: canbet & iasbet) even carry incomplete
WR over from one casino's account to the other!
I'm not sure why they do this. Tax reasons? Broader customer base? Baiting re-sign-ups by problem gamblers who have previously closed a "partner" account? Maybe it makes the
brand appear
bigger? Maybe researchers have found that some people will only play at "palace" themed casinos, some only at "ruby" themed casinos, some at "mummy" and some at "pig" themes???
Whatever the reasons are, it must be pretty easy to knock up a new logo and a flash animated splash screen and call it a new casino, so I suppose the small outlay quickly pays for itself if it means that "joe (gambling loving and pig loving) public" can now combine his two favourite things!