Comic Strips

What you're talking about is an important part of the challenges of translation between cultures and languages. Words for categories don't always translate neatly.

Take, for example, the English words for Lemon and Lime. Many languages don't distinguish between the two, and at most will call the lime a green lemon.

The word for "seafood" in many other languages may inherently exclude freshwater fish, or all fish, whereas in American English it usually includes all fish.

The two English categories of "bread" and "pastry" map onto three categories of "pain"/"viennoiserie"/"pâtisserie" in French, because enriched breads aren't considered bread.

Many languages don't have a different word between red and pink, and instead just call pink "light red" or something. Some languages distinguish light blue from blue, and may define the demarcation between green and blue differently.

I'm pretty sure there are languages that don't distinguish between alligators and crocodiles, goats and sheep, turtles and tortoises, too.

With cultural mythologies, it's especially interesting on whether we decided to use the same words for the different culturally independent myths: dragons, vampires, zombies, ghosts, demons, devils, gods, demigods, fairies, wizards, etc.

And so when talking about whether a culture or language distinguishes between mermaids and sirens, or whether they're considered the same thing, is just an extension of the broader observation that not everything translates neatly into the same categories across all languages.