ChatGPT is a general-purpose language model: you type a prompt, and it returns text. It has no access to your CAD models, drawings, BOMs, or company standards unless you manually paste that information into the chat window. An AI agent, by contrast, is a workflow-specific system that uses a language model plus direct access to your engineering data to produce a reviewable result. For example, an AI drawing review agent like CoLab's AutoReview reads native 2D drawings, checks title blocks, cross-references views, flags dimensioning and GD&T inconsistencies, and generates visual markups — all guided by your organization's specific standards and checklists. The distinction matters because ChatGPT requires the engineer to be the integration layer, manually abstracting and re-entering data, while an agent operates directly on the engineering artifacts within an established workflow.