It's very much the same planet. It orbits the same star and it has the same moon. But with different landmasses and nations, the creator of the story gets to take many liberties. The use of a Fictional Earth means that past and present real world history doesn't have to affect the story and absolutely anything can be made up. The story's nations may have real world counterparts. These worlds will usually have real world physics, but not always.
The planet has to be identified as Earth at some point, otherwise you're just dealing with a Constructed World that may or may not look like Earth in some aspects. Alternate History settings that are geographically different enough may overlap with this, if the country or continent boundaries changed, especially after a traumatic event.
Compare Earth All Along, where a planet seems alien at first but turns out to be a version of Earth. Contrast Earth Drift, where a setting starts as Earth but gradually becomes a fantasy world as the series goes on. Like Reality Unless Noted is when the difference with our Earth is minimal and mostly about events and characters.
- According to Takeshi Shudō's novels Pocket Monsters: The Animation, the Pokémon anime takes place on a futuristic Earth where Pokemon are aliens who replaced most of the wildlife. Also Hollywood was in Kanto. This made sense back when Kanto (named after Kanto, Japan) was the only known region, less so after the Earth Drift that started with Generation II. How canon the books are compared to the anime is debatable anyway, since they're a mix of behind-the-scenes details, commentary and Alternate Continuity.
- J. R. R. Tolkien's Arda is meant to be Earth in a fictional ancient time period. However, its geography is clearly fictional.
- The Deltora Quest Shared Universe takes place on the "World of Deltora" with hundreds of fictional islands including Deltora, Maris, and Dorne all located in seven seas. While humans are a predominant species there also many more fantastical creatures from gnomes, dragons, Fish People, and Capricorns to make a few.
- French-Canadian children fantasy series Amos Daragon lives and breathe this trope, with the world being very different from Earth geographically and populated by all manners of mythological creatures from all around the world while also featuring real-life civilizations and peoples like Sumerians, Dogons and Vikings and gods like Odin and Seth.
- Downplayed in Kushiel's Legacy: there are fictional countries, but the map is almost identical to Earth's except for a few alterations thanks to more actively involved divine forces in its history. Real countries are known by different names, though. It also overlaps with Alternate History, from the fall of The Roman Empire onwards. Significantly, the equivalent of the English Channel has the islands of the Three Sisters, where the Fallen Angel Raziel is bound beneath the ocean.
- In the world of The Rithmatist, North America consists of sixty islands instead of a continent, all of which are part of the United Isles of America. We don't hear much about the rest of the world, though the sequel will focus on Central and South America.
- The world of The Wheel of Time is strongly implied to be a distant and different future Earth, as the setting has an Eternal Recurrence of seven Ages that fade into history and come anew. Thanks to the Breaking of the World, an ancient supernatural cataclysm that rearranged the continents, the maps look completely different; but there are quite a few references to Earth history and myth, as well as a few ancient artifacts that originate in present-day Earth.
- The world of A Song of Ice and Fire is based on Earth with some key differences. For example, Westeros basically corresponds to Europe both culturally and in size, but is similar to a re-arranged map of Britain. Essos is Asia and Sotheros is Africa. Some fans especulate that another continent corresponding to the Americas is yet to be discovered.
- Warhammer Fantasy: The world map is clearly based on Earth's◊, though it has a few extra islands and geographical features Earth does not, such as North America being either frozen tundra or burning desert, Africa being split in two by a mountain range, and Antarctica being a warm wasteland populated by beastmen. In early editions, Warhammer 40K was set in the far future of Warhammer Fantasy, but they now exist in separate realities linked by the Warp, and 40K's Earth is now our far future.
- Ace Combat is a prime example of this trope. It's Earth in every possible way except for landmasses and nations. You can even tell what real world counterparts the nations are based on. It has an Antarctica no different from the real one. It even has its own Pacific and Arctic Oceans. Almost all the aircraft used in the game exist in reality.
- Civilization always takes place on Earth and uses its cultures, and most of the games have an option to replicate a real world map, but it's also possible to use a randomly-generated map that looks nothing like the real Earth.
- Dragon Master: Seems to be in effect given that the map shown during intermissions between fights lacks any similarity to any areas around the Pacific Ocean and especially not the world map.
- The world of Final Fantasy IV is named Earthnote . The landmasses are definitely not ours◊. The surface where most people live is named "Overworld" and the inside where Dwarves live is the "Underworld".
- The world of Pokémon is an interesting case. It was identified as Earth in the first generation, mentioning real world events and locations in Pokedex entries and naming Kanto after the actual Kanto region of Japan. However it is geographically completely different and real world mentions were dropped from Generation II onwards. But pastiches of real countries still turn up every generation: Unova is inspired by New York City and New Jersey, Kalos by France, Alola by Hawai'i and Galar by Great Britain. The implication seems to be that the Pokémon world is a Fictional Earth that doesn't really mention the Earth part anymore.
- Sonic the Hedgehog takes place on Earth, however the geography is completely different and countries are replaced with Fantasy Counterpart Cultures. There are also giant talking animals living amongst the humans.
- Super Mario Bros.: In Super Mario Odyssey, Mario travels a planet that resembles Earth, but with different landmasses and kingdoms inspired by real countries. The Mushroom Kingdom (the main setting of most Super Mario Bros. games) is found on a landmass that resembles a 1-Up Mushroom. The continents resemble the Earth's at some point in history, with three looking vaguely like Pangaea, Laurasia, and Gondwanaland. There's also no land at either pole, with the landmass the Snow Kingdom is on ending close to the north pole, and the south pole being completely covered in ocean with the nearest land being thousands of miles away.
- The Earth of Avatar: The Last Airbender is divided into four elemental nations. It is drastically different in terms of continent placement, with a landmass at each of the poles, and the Earth Kingdom being possibly bigger than our Eurasia. There's no equivalent for the Americas, Australia, and other continents.
- Steven Universe takes place on an alternate Earth with a number of subtle differences - in the US, for example, money has diamonds on it instead of Presidents' faces, and the center of the film industry is in Kansas. More importantly, the world map is quite different: part of Africa is attached to South America, and large amounts of real life landmass is instead covered by the ocean, including the majority of northern Asia. The latter is implied to be a result of the Gem Homeworld's Hostile Terraforming. The former seems much older.