As said here regarding the comparison between the two engines, it’s mainly just personal preference on what to use. Recently, the demand for Unreal Engine, in my sector, has been dramatic so naturally, we’re adopting it and using it to keep up with the trends of services to offer clients.
If you want to find out anything more about Unreal as a whole, you can use this link to the official site and read more into it: Features - Unreal Engine