In Windows it is possible to mount an ISO file as a drive letter. This allows you to access all the files on it and install software from it just like a normal CD or DVD inserted into your computer.

Insert the USB drive into an open USB port on the computer that has the ISO file. Windows automatically recognizes and installs the USB drive. Click "Start," then select Computer and double-click ...

Windows 10 April 2018 Update: Here's what you can expect Double-click to open the ISO file as a virtual drive in File Explorer, then drag its contents to your recovery drive.