ChatGPT is a general-purpose language model — you type a prompt, it returns text. An AI engineering agent is a workflow system that uses an LLM plus direct access to your CAD models, drawings, BOM data, and company standards to execute multi-step tasks and deliver reviewable results.

The key difference is that an agent works on native engineering inputs (3D geometry, 2D drawings, your specific standards), runs structured checks without repeated prompting, and applies your rules consistently across every review.

ChatGPT can help you draft a technical email or brainstorm failure modes, but it can't open a STEP file, check a drawing for DFM errors, or cross-reference your company's design standards.

For a deeper breakdown, see The Engineering Leader's Guide to AI Agents vs. LLMs.