Updating your Android smartphone is usually done in one of a couple of different ways if you're the average everyday user. You either wait for Google to push the software updates down the line to your device manufacturer then to your carrier, and then to you as it comes to your device over-the-air, or you wait for updates to be available through a manufacturer PC client software, then connect your device to your computer to finish the job. If you're someone who uses a Nexus device, though, you have other options, like flashing the factory images that Google posts up to the Android Developers website. There's also the OTA images which usually find their way to the web soon after the first OTAs begin to hit devices, as someone inevitably posts the OTA links for consumption.
Now, Google is making things just a little bit easier (and more secure) as they will begin to post Factory Images and OTA Images for Nexus devices at the same time, essentially giving users the option of how to flash the latest version of the Android software. For those flashing the factory images, an unlocked bootloader is required, and not all Nexus users want to unlock the bootloader due to security concerns, of course, there are other reasons as well. This is where the OTA images come in handy, and now Google will post them for users so they don't have to wait.
Users will begin to see these changes with the upcoming security patch update for June, and of course, when new versions of Android, like Android N for example, are pushed out to the web. Typically, the factory images are posted up to the Nexus support page on the Android Developers site, then anywhere from a day to a few days later OTA images make their way to users and the web. With both options now being available, this should make the update process for Nexus device a lot faster. Although the process will be simple for grabbing these OTA images straight from Google just like with the factory images, there will be a box that needs checking which is essentially for users to accept the terms and conditions of downloading the image and flashing it.