WiiU:Wii U Model Differences
Some page content & researching collaboratively taken from io55.net's Wii U page with permission.
Unlike many other consoles, the Wii U never received any major console revisions. The only models that exist are the two initial launch models, with the only difference being the internal storage space of the console. These two models were exclusively differentiated by their storage size. In terms of other hardware, they were completely identical.
WUP-001 - 8 GB Model
Available only in white, launching as the "Basic Set" or "Basic Pack". One of the two versions available at launch. At the time, this came with less additional peripherals, whist having only 8GB internal storage. A few minor reports also seem to imply that these may have NAND corruption issues, but it seems unsubstantiated. Otherwise, all is identical to the Deluxe.
WUP-101 - 32 GB Model
This model initially only came in black, and was knows as the Deluxe Set in North America and the Premium Pack in the rest of the world. About seven months after the console's initial release, an official white Premium Pack was released in Japan exclusively. This was the only way to purchase a brand new 32 GB white console. However, in North America, Nintendo sold refurbished white models with the storage upgraded to 32 GB, along with the model code WUP-101.
References
https://en.wikipedia.org/wiki/Wii_U
https://io55.net/wiki/eop/video_game_consoles-home/8th_generation/nintendo_wii_u
https://www.reddit.com/r/wiiu/comments/7oo3wb/any_particular_wii_u_model_to_get/ (mem?)