The difference between these two m.2 wireless cards is that the NGWMG.S is denoted as "Low Power" and the other is not. I think the S stands for "Smart", whereas the non-S version is Classic.
Intel® Dual Band Wireless-AC 8265 Product Specifications
(Click on Ordering and Compliance)
Is there any downside to the "SMART" version, or is it all gravy? I have a desktop, so I don't care about power consumption. So, in my case could this low power feature actually be a limiting factor in some instances (i.e. weaker signal as a trade-off for lower power consumption, less compatability with legacy Bluetooth devices, or perhaps less bandwidth than Classic)? In summary, are there any trade-off's I need to make if I go with the S version.