@dooz
as some already explained Aros 68k works on both amiga hardware and UAE using its own kickstarts. You can execute basically any 68k software written and compiled for 3.x as long the needed libs are implemented. You can even add libs or replace existing ones like replacing Zune with MUI 3.8 what I do in my distribution. Of course when using Zune you can also run Aros specific software.
On the other platforms (X86, X64 and ARM) you can only run Aros software compiled for the specific platform. You cannot directly run 68k software in X86 because there is nothing like Petunia but you can use UAE for it.