The NUC8, like pretty much every small form factor pc, uses a mobile cpu, whereas the new mini uses desktop cpu’s. You have to look at the top model nuc8 with i7 to outperform the entry-level mac mini with the i3, and then the price advantage disappears.

That CPU power comes in handy for most of the mini’s use cases, transcoding for home theater / nas, or build times for build server.