Abilities: flavor text and a couple of name changes.
Items: 15 new items, a few name changes, several price changes, and flavor text. Note that a couple of slots were replaced by different items (notably HM01-HM08 in sword/shield are now TM93-TM100), so item_game_indices is missing this information. A schema change would be required.
Moves: flavor text, a few name changes, and for whatever reason glacial lance is now 120BP instead of 130.
Pokédex: it's the same as the one from DP
Pokémon: flavor text, learnsets, several base_happiness and base_experience changes, the minimum happiness to evolve is now back at 220, burmy forms names in chinese and jpn_kanji, several genus changes (mainly in german).
item_game_indicesis missing this information. A schema change would be required.