Both are Autodesk CAD products, but they are optimised for materially different workflows. The fastest way to choose is to identify whether your design master is a 3D product model or a DWG drawing.
Fusion is positioned by Autodesk as an integrated product-development platform combining 3D CAD, CAM, CAE and PCB. AutoCAD is strongest when the job revolves around precise 2D/3D drafting, DWG documentation, annotation and industry-specific drafting toolsets.
“CAD” is too broad a category. Buying AutoCAD because it is the best-known CAD name can be inefficient for parametric product design; buying Fusion because it includes many engineering functions can be unnecessary if the actual job is controlled 2D DWG production. Choose around the dominant deliverable.
