Xbox One game is huge. Red Dead Redemption 2 alone is 107 GB. If you have a data cap then downloading the same game is a waste of time. Instead, your games transfer between consoles with external devices to save data.
Copy your games to save time and data
When giving someone a new Xbox One, we recommend installing games for them first. Whether it's a Christmas morning surprise for your kids or a birthday present for your spouse, their games will be ready to play instantly. When you play an Xbox game for the first time, the console instantly races most of the disc to the hard drive. Your Xbox downloads everything else needed to play the game. Incredibly, the extra content can lead to games of 100GB or greater like Final Fantasy 15, Gears of War 4 and Call of Duty: Infinite Warfare.
If you have more than Xbox One, you can install your games on each download several times but depending on your internet speeds that can take a long time. Even worse, if you have a data cap, you risk going over. For example, Comcast controls a 1TB (1000GB) data cap and a single Xbox One game download can use a tenth of it. Thankfully, Microsoft has added external hard drive support for the Xbox One. And while you usually use this to expand storage, you can also use it to move or copy a game from one Xbox to another.
This is also useful if you are upgrading to an Xbox One X from an original Xbox One or Xbox One S.
To transfer each game immediately (or just a few)
Transferring your games is one quite simple business. First, connect the external device you plan to use and format it if you are asked.
Warning : The formatting process deletes data on the device.
Microsoft requires you to use a USB 3.0 drive with at least 256 GB of storage space. In view of the large size of games, we recommend that you get at least one TB unit.
From the Xbox start screen, press the Xbox button on your controller (the circular button with the Xbox logo that lights up).
Select "System" and then "Storage". 
Here you select the hard disk currently being played. If you have never used an external hard drive before, select the Internal option. We choose "xbox" hard drive.
In the submenu that appears, select the "Transfer" option.
Select the individual games you want to upload or select "Select All" to transfer all games. Select "Copy Selected" to copy game files to the external device. You can use "Move Selected" to move the game files to the external device and remove the source copy from their original location, but you only want to do that if you free up space, such as a full internal hard drive.  You may notice that at the top of the screen, games are being transferred to your internal device, but don't worry about it. The next step asks you for a destination.
Select the device to transfer your games to. In this case, we choose an empty external hard drive named "External2."
You will see a confirmation indicating the number of games to transfer. If the information is correct, select "Copy" or "Move". The displayed option is dependent on your previous choices. If you used the "Copy" option, your games would exist on both the destination drive and the source drive. If you used "Move", your games will be wiped from the source source and moved to the destination drive. Double check your choices before moving on.
Xbox One starts copying or moving the game files to the external device. However, you will not see a confirmation or progressive bar. If you press the Xbox button, you should see the first game being transferred.
Depending on how many games you transfer and the speed of your external storage device, it can take anywhere from a few minutes to a few hours. To check if you have any games that are still being transferred, go to "My Games and Apps."
Select "Queue" in the sidebar. If you have any games left to transfer, they will appear here
Depending on the speed of your external storage space and your internet connection, copying your games from one device to another may be faster than downloading them again. But more important is that you avoid crossing a data cover if you have one.