People have mentioned the service - there's no 'napkin over a tray', you get a proper tablecloth, and each dish is brought to your table individually. Not only is the menu selection larger, you get full choice - want to try all the starters? Fine. Two mains? No problem. Cheese AND dessert? It's almost expected.

Aside from the food, though, the big difference for me is the that the personal space in F is WAY more than you get in J. The seats are much further apart (E/F pairs aside), so it's private without being claustrophobic.

Note that you don't get AVOD and videos - the players are removed as part of the NGCW refit.