The core differences between Claude Opus and the newly released Claude Fable 5 revolve around autonomy, reliability, workflow mentality, and pricing. - Shift from Micro-Management to Autonomous Goals: When using Opus, users typically had to guide the model step-by-step, assigning micro-tasks and building out features one by one. Fable is designed to operate autonomously using "loops". Instead of telling Fable what to do next, you give it a high-level, massive end goal, and it will independently find its way there to build complex projects all at once. - Trust and Bug-Free Generation: With Opus, the standard workflow involved assigning a task and constantly checking to see if the model did the work right or produced buggy code. Fable shifts this mentality entirely; it is highly reliable and builds without bugs, meaning you only need to verify that it is doing the "right work" rather than checking if the work itself is functional. - Acting as an Equal "Thought Partner": While Opus was largely treated as a tool to execute commands, Fable operates at a level of "super intelligence" where it should be treated as an equal collaborator. Users are advised to lean on Fable for advanced planning, asking it questions about how to approach a build or having it fully flesh out an idea before writing any code. - System Settings and Token Usage: Because Fable does a tremendous amount of deep thinking, it "torches tokens" much faster than previous models. In the Claude Code CLI, the recommended /effort setting for Opus was typically "extra high," but for Fable, the recommendation is to lower the effort setting to "high" to start. - Pricing and Subscription Availability: Fable is double the price of Opus when used via the API. Additionally, Fable will not be permanently available as part of a standard monthly subscription; it is only available to subscribers for a two-week promotional window (until June 22nd), after which users will be required to pay for it entirely via API usage.