Yes, there's an actual geographical world that all of the games take place in.

And more or less it's the same world every time, with the specific details being different for the sake of gameplay. Zelda (as are all Nintendo games) is designed with gameplay in mind first, and story/lore/world being in second. Which is why it tends to vary.

But in the map I posted, that little bit down at the bottom (the zoomed in part), that's "Hyrule" for 99% of the games. The zoomed out part consists of "greater hyrule" which is only really explored in Zelda 2, after Hyrule is disbanded and the people spread out.

The islands off to the right of that map shouldn't actually be there. The islands are actually just the mountains/high points of the map, after the world is flooded. And they should really be overlaid on top of lesser/south hyrule. That's why I said the map was inaccurate.

As for termina, my personal theory is that it is underneath (literally) Hyrule. Similar to Subrosia and how the pirate ship sticks through the world.

Pic 1:

http://static2.wikia.nocookie.net/__cb20090616033533/zelda/i...

Pic 2:

http://static2.wikia.nocookie.net/__cb20090616033629/zelda/i...

We know subrosia is beneath/under Holodrum. And judging by how you get to termina from hyrule, it seems to be a similar case. And the stone tower with it's reversed gravity just strengthens the argument. And with the release of Link Between Worlds, you can see that the concept art also shares this idea:

And in lorule (underneath hyrule) there are many similarities and hints towards termina. Like the crazy mask people, the parallel people, and the dismissing of the gods and triforce.

So yea, they dismiss a bit of geographic detail in favor of gameplay. But most of it is relatively the same. You have death mountain in the north, lake hylia to the south, and the gerudo desert to the west. Castle town is northish, and lon lon ranch is smack dab in the middle. Then you got lost woods and kakariko village.

Sure, they shift around a bit, but they are generally in the same relative locations.