AI skills vs. Custom GPTs: what's actually the difference?

When people first hear about Skill Tree skills, the first question is usually: "how is this different from a Custom GPT?" It's a fair question. Custom GPTs, Claude Projects, and Skill Tree skills all involve writing instructions that shape how an AI behaves. Here's where they differ.

What they have in common

All three — Custom GPTs, Claude Projects, and Skill Tree skills — work by prepending a system prompt to the model's context. That prompt sets the AI's persona, constraints, output format, and domain knowledge. The core mechanic is identical.

Where Custom GPTs fall short

• ›Locked to ChatGPT — can't be used with Claude or other models
• ›Shared publicly by default — your prompt is visible to OpenAI and other users
• ›Discovery is chaotic — the GPT Store has tens of thousands of low-quality entries
• ›No versioning, no updates — you get whatever the creator last saved
• ›No CLI install — you have to navigate to the URL every time

Where Claude Projects fall short

• ›Requires manually writing and managing your own system prompts
• ›No packaging, no portability — prompts live in Claude.ai, not in your workflow
• ›Can't be installed into Claude Code, which is where heavy users spend most of their time
• ›No sharing or reselling — prompts stay siloed per account

What Skill Tree skills do differently

• ›Works with both Claude and ChatGPT — one purchase, two platforms
• ›Installs via CLI directly into Claude Code — no copy-paste
• ›Engineered and tested prompts — not user-written first drafts
• ›Versioned and updated — when we improve a skill, you get the update
• ›Curated catalog — every skill ships because it actually works
• ›Portable — your skills travel with your config files, not locked in a browser tab

When to use each

Custom GPTs are fine for casual use when you're already in ChatGPT and the task is simple. Claude Projects work for personal context files and knowledge bases. Skill Tree skills are the right choice when you want a specific capability that works reliably, installs cleanly, and follows you across tools.