What's actually different
The differences are short. Here they are, honestly.
Different company, different model. The Claude CLI runs Anthropic's Claude models. The Codex CLI runs OpenAI's GPT models, the same family behind ChatGPT. Both are strong at coding work. Neither is permanently ahead; the lead changes with each release. You don't need to track which is winning this month. You need both installed so you can use whichever fits.
Different sign-in account. The Claude CLI signs in with a Claude account. The Codex CLI signs in with a ChatGPT account. If you already use ChatGPT, that's the account. If you don't have one, you'll make a free one during sign-in. Different door, same kind of door.
A slightly heavier install. The Claude CLI had a one-line installer that needed nothing set up first. The Codex CLI installs through a tool called npm, which comes with a program called Node.js. If you don't already have Node, that's one extra one-time setup step. It's small, the next lesson walks through it, and on a Mac there's an even simpler option. Just know now that the install has one more part than Claude's did.
Some defaults and wording differ. The two tools name a few things differently and start with slightly different default settings for how freely they act before asking. None of it changes what the tool is. When you sit down in front of Codex, you'll see familiar ideas with a few unfamiliar labels, and you'll adjust in a minute.
That's the whole list. A different model, a different sign-in account, one extra install step, and some cosmetic differences. Everything that makes the tool the tool is shared. The next step is the one that actually matters in practice: deciding when to use which.
What's actually different
The differences are short. Here they are, honestly.
Different company, different model. The Claude CLI runs Anthropic's Claude models. The Codex CLI runs OpenAI's GPT models, the same family behind ChatGPT. Both are strong at coding work. Neither is permanently ahead; the lead changes with each release. You don't need to track which is winning this month. You need both installed so you can use whichever fits.
Different sign-in account. The Claude CLI signs in with a Claude account. The Codex CLI signs in with a ChatGPT account. If you already use ChatGPT, that's the account. If you don't have one, you'll make a free one during sign-in. Different door, same kind of door.
A slightly heavier install. The Claude CLI had a one-line installer that needed nothing set up first. The Codex CLI installs through a tool called npm, which comes with a program called Node.js. If you don't already have Node, that's one extra one-time setup step. It's small, the next lesson walks through it, and on a Mac there's an even simpler option. Just know now that the install has one more part than Claude's did.
Some defaults and wording differ. The two tools name a few things differently and start with slightly different default settings for how freely they act before asking. None of it changes what the tool is. When you sit down in front of Codex, you'll see familiar ideas with a few unfamiliar labels, and you'll adjust in a minute.
That's the whole list. A different model, a different sign-in account, one extra install step, and some cosmetic differences. Everything that makes the tool the tool is shared. The next step is the one that actually matters in practice: deciding when to use which.