I bought my first studded tires 11 years ago: Nokian Hakkaplitta W106 (they have 106 studs) in the 700x40 size. If there were other decent studded tire options back then, I didn't know about them. Those Nokians were heavy and slow and not much fun, but they did allow me to commute through the winter on streets and bike paths without any serious crashes. I also learned that winter riding involves a huge variety of surfaces conditions, and no tire is perfect for all of them.
Back when we had few options, we didn't have much need to scrutinize our studded tires. But now, we have lots of choices, and we can spend at least a few minutes over-analyzing. The classic type is shown here:
Here's what a 45NRTH Xerxes looks like. These tires have been in stock at HC since last year, so I'm not sure if this is still representative of the current Xerxes tire.
Finally, this is the tread of a 45NRTH Dillinger (26x4" or 4.8"), but it's pretty similar to the 45NRTH Nicotine 29x2.35", which, in my experience, is an amazing tire.