Thinking about the phylogenetic connection between the Lost Worlds of Victorian adventure fiction and the planetary romances of last century led me to an overall classification scheme for all sorts of unusual/fantastic lands or country within large settings (whether that larger setting be an approximation of the real world or a secondary, fantasy world). This was quickly done, so it might bear further though.
The Strange Country: The Strange Country probably is an outgrowth of The Odyssey and Medieval travelogues. It is a place definitely situated in the wider world and generally not differing in its physical laws but possessed of its least one unusual feature whether than be a geographic anomaly, cultural eccentricity, or weird animal. Most of the various city-states of Barsoom, and the countries of Vance's Tschai or Raymond's Mongo fall into this category. The "Planet of Hats" TV trope is the Strange Country on a planetary scale. The Strange Country differs from the more mundane foreign land by the degree of exaggeration in its unique thing and by the fact that beyond that thing, it isn't usual that foreign in terms of culture, language, etc.
The Lost World: The Lost World is more remote and more divergent from the outside world that the Strange Country. Most often it's an isolated pocket of one or more elements of the world's past, but it could be completely alien. Perhaps its most defining feature is that it is typically a hidden place and is much harder to reach than the strange country. Maple White Land of Doyle's The Lost World is the prototypical example, but Tarzan encounters a lot of these "lost valleys" from Crusader to remnants to lost Atlantean cities. The dividing line between the weirder Strange Countries and Lost Worlds isn't entirely clear, but if the place is widely known to scholars just seldom visited, it's a Strange Country. If no one knew it existed or it was believed to be mythical, it's a Lost World.
Fairyland: The Fairyland is a region defined by its fantasticalness. Physical laws may be very different from the surrounding world. If it has contact with the wider world if is limited and geographical conscribed. Often though, it will be as remote as the Lost World--even more so, perhaps, because it may not strictly be placeable on a map, existing in an extradimensional space. Literal Fairy lands are generally Fairylands, but so is the demonic subworlds of a number of Michael Shea's fantasy novels, Hades in Greek Myth, or Wackyland in Warner Bros. cartoons featuring the Dodo.