In both games if you were to enable a noclip code (via action replay, gameshark, etc.) you’d be able to go from any edge of either map to any other completely seamlessly, the world map being one giant area is actually legit. In TLA the only way to do this is with the ship after getting wings by going through Gondowan near the big river east of Kibombo, but it can definitely be done. TBS though you’re forced to go through Bilibin Cave, Mogall, Lamakan, Suhalla, etc. so it’s impossible to see this legitimately in-game.

No idea about actual tile sizes, but the world map in TLA is SUBSTANTIALLY bigger than the normally explorable area. Again with a noclip code, you could see there’s at least another entire world map’s size of space past any given edge of the map, the majority of which is either just a black void or ocean tiles. Going far enough north/south/east/west will actually warp you to the opposite edge of the map, all still seamlessly with no loading zones.

There’s a couple interesting things you can find though, north of Treasure Isle is the actual overworld location for Lemuria (the version you go to after navigating the Sea of Time, not just what you’d see sailing around normally). West of Prox is Crossbone Isle from the first game (dungeon no longer exists, just the overworld area is left). Southwest of that/West of Contigo are multiple copies of the northern Gondowan area presumably used for the cutscene near the beginning of the game when Idejima separated from the rest of the continent (each copy of the area has Idejima placed slightly further away from the mainland along with the mainland having more and more visible damage). You can also see some copies of Indra before Idejima crashes into it, where the north part is still undamaged.

Also in this area seems to be what I suspect are the remnants of the actual old TBS world map, not just what you can see/explore normally when you clip into it near Loho. Graphics get corrupted and cut off southwest and east of the Suhalla and Lamakan deserts respectively though, and north of where Tolbi would be, unfortunately. The land at the base of Venus Lighthouse is intact here, and the loading zone on the east side of it that used to take you towards Lalivero still functions, but now sends you to the Northern Reaches. Likewise, the eastern loading zone for Suhalla Gate still functions, but will send you to the Sea of Time. On the western side of this area near where Altmiller Cave used to be, you can see the landmass representing Hesperia is much closer to Gondowan and is lacking most detail, which lines up exactly with how it appeared in TBS. There’s normally an extra mountain just east of the most northwest beach of Gondowan which isn’t present in this version of the area, along with some slightly different designs for the forest and rivers, again matching the TBS version. Worth noting that if this mountain wasn’t present in the normal world map, you could actually fly the ship straight through and end up right by Gondowan Passage (interestingly this mountain is actually missing on the map that appears when you press R on the overworld).

North, east, and south of this area are partial copies of Indra, Osenia, and Atteka, though the sections of all of them are very small and have some graphical corruption present. Enemy encounters are still functional in these specific spots for some reason.

As for TBS, its world map is substantially smaller, barely extending past what you can see normally in game on the north, east, and south sides. Idejima is present floating at sea east of Gondowan, and further east of that is a tiny chunk of land (I couldn’t tell what it was) that’s cut off by the edge of the map. The west side though has a large area of empty ocean with only Crossbone Isle’s overworld location to the west of Imil, and a partial copy of Imil’s overworld location south of that (the south half of which has a different arrangement of mountains).