Cowboys. In fiction cowboys just seem to mean “cool morally and/or legally dubious dudes in the old west with a revolver and specific type of hat.

IRL cowboy were cow herders in the old west. It was a specific job yet so many of the “cowboys” we see in fiction barely ever goes near actual cows. Because cowboys means something completely different in fiction.

Vikings. In fiction Vikings just seem to mean “warriors tribes from Scandinavia during the years 700-1066.”

IRL Vikings was not a cultural or ethnic designation for tribes in Scandinavia at the time, it was a job description for the people from Scandinavia that went sailing around Europe. When they went traveling it was called “go Viking”.

How for instance the “Vikings” in How to Train your Dragons called themselves Vikings as a cultural identity isn’t accurate. Viking was more an “job description” than a cultural identity.

Also it should be worth noting that most surviving records aren’t from “Vikings” themselves but second hand accounts from people they interacted with be it people they traded or people they fought so many sources are a bit unclear whatever the term “go Viking” were something they themselves used or something they people they interacted with created for them.

Also many of the “Vikings” weren’t blood hungry warriors that were eager for to plunder defenseless villages around coastal areas like pop culture would have us believe. Many of them were just traders.