The Mac Mini is using full desktop components, not NUC laptop components. That's why it supports 4 times as much RAM, Thunderbolt 3, and a 65 watt CPU compared to the 25 watt NUCs.
2× (64GB v. 32GB)
> Thunderbolt 3,
NUC also supports Thunderbolt 3
> and a 65 watt CPU
Well, okay, that one is right.
Modern high-end NUCs use 100W CPU, this one: https://ark.intel.com/products/130409/Intel-Core-i7-8809G-Pr...
i5-8259U, 4 cores, 8 threads, 28W TDP
i7-8559U, 4 cores, 8 threads, 28W TDP
i7-8705G, 4 cores, 8 threads, 65W package TDP
i7-8809G, 4 cores, 8 threads, 100W package TDP
The last two have fancy integrated graphics and only come in a larger form factor with a skull on the side.edit: conciseness, formatting