Taking a prototype to a real product is where AI app builders stop looking similar. Codex and Emergent can both help you get from prompt to working software, but they diverge hard on the job that matters next: turning a promising draft into something you can secure, test, deploy, and keep changing without losing the plot.
That job exposes the failure modes that actually hurt. Once auth, database rules, API wiring, and repeated fixes enter the picture, the question is no longer who can generate screens fastest; it is who leaves you with fewer hidden liabilities when the prototype has to become a maintained product.