Pickups: What you see (and hear) on the Elitist Casino are 'standard' Gibson P-90s, while the ES-330 pickups are the underwound CS variety. For what it's worth, both necks felt different, but very comfortable to me. It's not exactly a slim neck in modern terms (when comparing it to a 'shredder' guitar) but noticeably slimmer than the neck on the ES-330, which is more like a '50s style Les Paul neck and VERY substantial. In Gibson terms, what's on my LP is called a '60s slim taper neck. Neck: I own a Gibson Les Paul Classic (from the '90s) and to me, the necks on that guitar and the Casino feel VERY similar. plastic pickup covers etc) are the neck shaping, the pickups, the ABR-1 bridges and the finishes. I think the biggest differences between those two guitars (aside from the cosmetical aspects like the different headstocks, the metal vs.
To start off, I think both guitars are excellent and I don't think anyone could seriously go wrong by leaving the store with either of them.
All of this is strictly imho, so bear that in mind. When mentioning the ES-330, I'm talking about the recent Custom Shop VOS version. Here's my 0.02$ since I lately was in the market for either an ES-330 or an Elitist Casino as well (and ended up with an old Jazzmaster, but that's a different story).