I see FreeCad as the perfect solution for a startup with limited resources that want to save as much as possible and doesn't mind using non-standard 3D CAD software, i.e., it's not required by customers to use specific software for compatibility. It's perfect for hobbyist use and makers who don't care about brands and pay monthly fees. I see it as very well suited for small businesses that need FEA (finite element analysis) and can't/don't want to pay huge amounts of money for it, just like us. I see FreeCad as less appropriate for big corporations or well-established businesses that need standardized solutions, compatibility with clients or good version management. Don't get me wrong, it can get the job done, but it will be much slower than state-of-the-art CAD systems.
Unity is excellent for 2D and 3D games and educational experiences. It is well-suited for VR and AR development. It is also a great platform for mobile games. It is less-suited for non-game purposes (although it can certainly be used for those as well), or educational experiences. It is also less-suited for AR experiences that are highly complex, where you will probably want to write the native code in Android Studio or Xcode, as the case may be. It is theoretically less-suited for cases where performance is a huge concern as well, although, in my experience, performance has never been a problem.
Unity is a multiplatform game engine. It has more than 20 options for exporting your game, ranging from desktop, mobile, console, web and, lately, VR and AR. Unity was one of the first game engines able to export games playable on internet browsers and it helped to cement the World Wide Web as a place fit for gaming.
Unity has a very smooth learning curve for beginners. It is easy to start and soon you are seeing some tangible results of your efforts. The game engine has all sorts of helpers and shortcuts to facilitate some frequent tasks in game development.
Another of Unity's advantage is the access to Assets Store from within the game engine, allowing the user to import instantly objects, scripts and textures from the store into their projects. Such easy access to these elements from inside a project greatly enhances speed production and is particularly helpful to beginners.
Usability is awkward. Perhaps if you learn it as your first CAD, it will feel OK. Still, it comes from commercial CAD products like mine (Onshape, Solid Works, Inventor, Solid Edge). You will feel it is less intuitive, with a less polished UI, difficult to customize and, this is a subjective one, less serious. I'd love to see it improve the usability and UI. I believe the engine behind it is powerful, but how you interact with the software is still lacking.
It's actually incredibly easy to use given the complex tasks you have. Once you learn the various windows it becomes second nature. Compared to something like Blender (which I would probably rate as a 2 on usability), the learning curve of Unity is a breeze! The only improvements I can think of would be to streamline some common workflows so you don't have to dig through menus to find them.
I have not had to use Unity's support extensively. This is likely because there is so much documentation and so many classes available for free online. Due to this, there is little need for support. They were very responsive when I requested educational licensing. Setting it up and providing it all quickly.
Freecad is used often when receiving files from multiple sources and the need to work with cad in various forms from meshes to solid cad. Often when receiving scans of 3d objects the format is easy to work with and convert to traditional cad later on. There is no other cad that can bridge the gap between all the cad formats that we found yet.
We love utilizing unreal engines but we seem to have a better use case for the architectural visualization side of things. This has given us the ability to find better more photo-realistic assets from not only the marketplace but 3rd party sites that have a unity bases file to work off of.
