Default TouchWiz Update

Hi guys,

New to the forum and new to samsung galaxy devices, so I am after abit of information.

I currently have a GS4A running 4.4.2. I noticed the new GS5 has an updated TouchWiz and I was curious if there was any way to update the GS4A's TouchWiz to the GS5's? Or do TouchWiz updates come alongside firmware updates?

Thanks.