The key to FireMonkey cross-platform support is its rendering architecture. When you create a new multidevice project with Delphi, on the first page of the wizard you can choose an application type. This effectively just selects the type of the first form to add to a new app. You can choose Blank Application. This will add to the project a form inherited from TForm, which is a basic two-dimensional form. The second choice is 3D Application. This will add a form inherited from TForm3D. All other choices give you a TForm descendant with some additional controls already added. Check the following screenshot:
If you decide to add more forms to the project, then you can see the real choice. It is either an HD Form or a 3D Form. HD stands for High Definition and is just a different name for 2D. Depending on the chosen platform, FireMonkey forms are rendered using different...