What Are with All the Different GPT-5 Variants in Codex and How Are They Actually Different? (or are they even?)

OpenAI's Codex platform has become increasingly opaque as the company releases numerous GPT-5 variants with confusing naming conventions and minimal documentation. Users now face a labyrinthine interface where they must click through three separate UI elements just to identify which model they're using and adjust reasoning effort settings. The problem extends to model descriptions that read like "word salads"—vague marketing language that fails to clarify practical differences between offerings like GPT-5.1-Codex-Max (called the "flagship model"), GPT-5.4 (the "latest frontier agentic coding model"), and GPT-5.2 ("optimized for professional work and long-running agents").

Compounding the confusion, OpenAI's own comparison tools contain contradictory information. GPT-5.2 is labeled as the "previous frontier model" while GPT-5.2-Codex is called the "most intelligent coding model"—despite GPT-5.3-Codex already existing. Features like "configurable reasoning effort" appear in descriptions for some models but actually apply to all of them. The naming suffix "Max" in GPT-5.1-Codex-Max remains unexplained, leaving users guessing whether it indicates superior performance, larger context windows, or simply marketing terminology. This lack of transparency forces developers to trial-and-error their way through model selection rather than making informed decisions based on clear technical specifications.