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In the Trilogy, the game world is comprised of multiple interconnected 'sectors', which are typically located in different solar systems. Notable exceptions being Earth's solar system and the Albion system, which possess multiple sectors each. Trilogy sectors are joined together by a network of gates that can be flown through or jumped to (although broken gates could not be jumped to). Whichever sector the Trilogy player is in is rendered and other sectors are not. Thus a distinction is made between In-Sector (IS) and Out-Of-Sector (OOS). IS calculations/game mechanics are what the player's ship always experiences. OOS, things are simplified to save on computations since there are many sectors. Whilst simplified, OOS game mechanics aim to approximate IS conditions and outcomes,
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The game world is is comprised of multiple 'zones' that are be travelled between via highways or free flight, and they are sub-units of sectors. Sectors are travelled between via jump drives and (to Jump Beacons) or super highways, and there are multiple sectors per system. Zones are relatively close together within a sector and sectors are rather far apart within a system. Scale. Different systems are connected by gates. Travel-wise, the lore is that after X3:AP, all gate shut down. 30 years have since past and jump drives have evolved to jump between Jump Beacons within individual systems. At the start of Rebrith, the gates begin to activate and reconnect systems but with jump drives having changed, they need to be flown to and through. Scale-wise, a Rebirth zone is similar to a Trilogy sector. Rebirth zones are typically a bit smaller and have less stations than Trilogy sectors, although Rebirth stations are more akin to Trilogy station complexes. Travel-wise, the lore is that after the post-X3:AP gate shutdown, 30 years have past and so jump drives have downgraded to jump to Jump Beacons only. Gates connect systems but they've only just reopened and need to be flown to and through.
Getting back to the Rebirth engine, simplified mechanics are employed on distant things but the details are a little more nuanced. Due to the focus shifting from sectors to zones, the old IS/OOS terminology doesn't quite fit and although IZ/OOZ is a useful distinction in Rebirth, it isn't quite comparable to the old terminology in terms of the game engine. This is because the engine makes use of "Attention Levels" when deciding how to model what is going on.
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