Biome implements more ESLint rules than OXC: Biome implements about 90 ESLint rules [0], while OXC implements about 60 rules. This brings Biome closer to parity with ESLint. However, Biome has changed some rule names, uses camel-case rule names instead of kebab-case names, doesn't provide some rule configurations (to avoid configuration nightmares), and slightly changes some rule behavior (as OCV does).
[0] https://github.com/biomejs/biome/discussions/3