What is the difference between x8 and x16 RAM module?

Question

RAM

Situation: there is an intel nuc, I choose a RAM for it. It needs a "notebook" sodimm ddr4, there are 2 options: 4gb single rank, 4gb single rank x16.
The wiki has an article about memory rank. But I can't quite figure out what it is.
For myself, I understand this as something like a two-channel mode, in other words: faster, better. But is there any point to this in sodimm, and if so, is it more than 1-2%?
PS The price for x8 and x16 bars is the same.