The "geography" of the Americas has been something funny to me. When people speak of the continents they say Europe, Asia, Africa, America and Oceania. And they separate Europe and Asia (which is something cultural and not geographic) and put together South America and North America which are clearly separate continents.
Well, that's how we see it here (and, judging by your post, I gess it's how it's also how seen in Spain): 1 continent, "América", divided in three subcontinents (América del Norte, América del Sur y América Central). The "Anglo" world apparently considers the Americas TWO continents: North America and South America. I've started a thread about this issue in chat:
https://www.alternatehistory.com/discussion/showthread.php?t=92789. As I said there, I donsider that both views are equaly valid, it's just a matter of convention.
However when people speak about North America they include only the United States (and sometimes Canada) and exclude Mexico, Guatemala... and they create that fiction of Central America.
This bit (calling the Us and/or the US + Canada "North America") could be because, at least here, calling Americans "americanos" doesn't seem right, cause, Chilenians, Argentinians or Haitians (to name just a few) are
also living in América, and thus, they could also be entitled to that adjective. On the contrary, by calling them "
Norteamericanos" that inconvenient is solved. That doesn't solve anything, because Mexicans are also Norteamericanos. But that doesn't stop people for using these adjective.
However, this wouldn't explain why the "anglo" world also confuses North America with the US & Canada, and South America with Latin America (I've seen it on the forum on several cases). The reason behind this is that there is a cultural difference between Latin America and the US & Canada. The problem is that the cultural areas and geographical divissions do not much (no matter if you are speaking of "América" or "the Americas"). But there's a strong human tendency to simplify, which makes fighting against it a bit pointless.