I disagree with your assertion that Celebrity commands significantly higher fares. It may be higher up on the mass market scale, but is not what I would call a "premium" line. I think of those as Silver Sea, Raddison and the other smaller much pricier lines.
No, these are the "luxury" lines. Analysts traditionally divide the cruise market into the following four segments.
>> Budget lines generally were small companies operating older ships on "shoestring" budgets. They provided the basics at low cost, without frills, but cut a lot of corners in the process. Traditionally, lines like Commodore Cruises, Dolphin Cruises, and Premier Cruises were in this category, but most lines in this category been crushed by "Mainstream" lines cutting costs and fares over the past decade. Think of this as cookies and milk or, in automotive terms, the original Volkswagen Beetle.
>> Mainstream lines, which traditionally offered a solid product with few frills, evolved into the lower end of the "mass market" lines. This category includes Carnival Cruise Line, Norwegian Cruise Line, and Royal Caribbean International, though the latter seems to have moved up half a notch in recent years. Think of this as pretzels and beer or, in automotive terms, a Chevy or a Ford.
>> Premium lines generally sought the proverbial "knee of the curve" by operating at the proverbial "knee of the curve" where they could offer a fair amount of polish for a slightly higher fare. This category traditionally included Celebrity Cruises, Disney Cruises, Holland America Lines, Oceana Cruises, and Princess Cruises, though Princess Cruises seems to have slid down a notch due to the British parent company's "cost reduction programme" about five years ago (before the merger of operations with Carnival Corporation). Think of this as wine and cheese or, in automotive terms, a Buick or a Mercury.
>> Luxury lines generally spare no expense to achieve perfection in their product, and it's reflected in their fares. Lines in this category include Crystal Cruises, Cunard Lines Ltd., Regent Seven Seas (formerly Radisson Seven Seas), Seaborne, and Silvesea. Think of this as champagne and caviar or, in automotive terms, a Cadillac or a Lincoln.
I generally stick with this standard classification to minimize confusion.
We just sailed Jewel in June and it was every bit as upscale as our Celebrity cruises.
So Royal Caribbean serves champagne to boarding passengers?
And Royal Caribbean hands out cold towels to passengers returning to the ship in warm weather?
And Royal Caribbean serves "gourmet bytes" in all lounges late at night?
These are examples of the "extras" that "premium" lines might provide but that "mainstream" lines would not.
FWIW, food is a poor metric because it's very much a matter of personal taste. Conoisseurs often rate Celebrity's cuisine very highly based upon its French style, with its fancy sauces and such, but that's not so wonderful if you don't care for French cuisine. I have never had a complaint with the quality or preparation of food on Celebrity, but the French menus do grow old very quickly.
We are retired and not "wealthy" by any means and we don't spend any more on Celebrity than we do on RCI. To me they are pretty much interchangeable. (However, I know there are Celebrity-only snobs that are cringing at this observation.)
There may be some "snobs" on Celebrity, but most passengers seem to be pretty normal people who enjoy the finer things in life. Nonetheless, you really should cruise on whichever line better matches your preference of style.
The passenger demographics seem the same on both lines.
I don't have first-hand experience on Royal Caribbean so I can't argue this point, but that is not exactly what I have heard from other sources for similar itineraries.