Intelligent Delivery strips a game's assets down to data chunks that are individually tagged. There could be tags for 4K assets in a game or for each local language that is supported. So, if you live in the United States and play a game that is enjoyed by a world audience, like FIFA 2018, you would only need to download the English audio tracks instead of countless other languages that wouldn't add to the gameplay (like Spanish, Portuguese or French).
Likewise, someone that has an Xbox One S wouldn't be required to download 4K assets for a game like Forza Motorsport 7, which would otherwise be considered mandatory for an Xbox One X. Taking things a step further, if have no desire to join in on multiplayer festivities with Call of Duty: WWII (which is sacrilege, by the way), you could simply download the single-player campaign. If at some time in the future you tire of the campaign and want to get in some headshots in the multiplayer space, you would be able to download that portion of the game.
In essence, Intelligent Delivery means that not only are games downloaded faster, but it has the potential to save gamers a ton of disc space that would otherwise be wasted. The technology would also allow multi-disc games to be supported. "Logically, essential data is located on the first disc and installed first, with the Xbox system software prompting the user to insert further discs in order to install other data," writes Digital Foundry, which has analyzed documentation related to Intelligent Delivery.
"Optional 'chunks' can be included on additional discs, with the user potentially able to specify what content or languages they'd like to install."
While Intelligent Delivery has the potential to greatly streamline delivery and installation of games on the Xbox One family of consoles, it is up to the individual developer to implement it. That means that we will likely see support show up initially in first-party gaming titles, with big name publishers likely following closely behind.