AutoCAD still has constraint functionality, but it's a watered down version compared to Inventor. As well as that - I could be wrong - but I think it's limited to two dimensions.
AutoCAD focuses on creating drawings while FreeCAD is about creating models.
AutoCAD is mostly used by people who already know AutoCAD or have to work with AutoCAD drawings. Most engineers have migrated to a model based approach years ago.
In architecture and civil engineering, even with powerful BIM software like Revit and Archicad, AutoCAD is still widely used, and for good reason.
Any AutoCAD > 2006 (maybe 2004) is still very good today.
IMO the versions after 2008 are bloated with shoehorned 3d stuff that work better on other software and isn't the core of AutoCAD (vector drawings).
On top of that, Autodesk hasn't implemented HiDPI correctly on any of their products, making them borderline unusable on my otherwise beautiful 3840 x 2160 screen.
AutoCAD LT perhaps is the better comparison.
AutoCAD still does 3D. It's just the foundation for the MCAD BIM and Surface Modeling product verticals that dump a whole load of tools on top for those specific workflows.
