What makes a console "next-gen"...?

[Mazty]

Jay520 said:

Mazty said:

Wii -> Wii U ?
If you ignore hardware, then how can you determine the difference or similarities in consoles?

The Wii U can be considered next gen because it replaces the Wii. The Wii loses relevancy while the Wii U gains relevancy. Functionality is also important; there needs to be a considerable difference in functionality between two consoles in different generations.

What do you mean by functionality? And what if that functionality doesn't differ between rivals?