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 received one major revision with many minor revisions, however not publicly announced by Nintendo. The original motherboard included with launch consoles was the WUP-01, with WUP-30 and WUP-40 being minor board revisions. The WUP-50 was the last motherboard revision, which had a SoC revision and a slight board layout change. The only retail SKUs that exist are the two initial launch models, which were the WUP-001 and WUP-101. These two models were exclusively differentiated by their storage size and color. 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". It was one of the two versions available at launch. At the time, this came with less additional peripherals, whist having only 8GB internal storage. Otherwise, it is identical to the Deluxe.
WUP-101 - 32 GB Model
This model initially only came in black. It was known as the "Deluxe Set" in North America, and the "Premium Pack" in the rest of the world. This version of the console also came with a gamepack dock, gamepad stand, and two stands to orient the console vertically in the box. About seven months after the console's initial release, an official white Premium Pack was released exclusively in Japan. 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. Models that came with eMMC manufactured by SK Hynix (these only potentially appear in consoles from 2012 and 2013) are more prone to failure.
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?)