My understanding is that anglophones take it to mean any of the following depending on context:
- Canada and the U.S.: by far the most common usage in most contexts, the default definition.
- Canada, the U.S. and Mexico: usually only used when discussing some sort of political or economic aspect where Mexico enters the picture
- Canada, the U.S., Mexico, the various Caribbean islands and Central American countries: much rarer, usually only employed in geographic discussions or with regards to associations such as CONCACAF. In fact, this connotation is often self-referential in that the speakers will tend to mention or allude to the debate about the definition of North America in that very same context.
Is the above description accurate, and is there an underlying logic to it or additional connotations I might be missing?