I asked codex to write a summary about both code bases.
"Dev 1" Qwen 3.5
"Dev 2" Gemma 4
Dev 1 is the stronger engineer overall. They showed better architectural judgment, stronger completeness, and better maintainability instincts. The weakness is execution rigor: they built more, but didn’t verify enough, so important parts don’t actually hold up cleanly.
Dev 2 looks more like an early-stage prototyper. The strength is speed to a rough first pass, but the implementation is much less complete, less polished, and less dependable. The main weakness is lack of finish and technical rigor.
If I were choosing between them as developers, I’d take Dev 1 without much hesitation.
Looking at the code myself, i'd agree with codex.