Both methods of installing an i Phone update are pretty straightforward, so you should just choose the one that works better for you.
The world of mobile software doesn’t sit still for anybody, so i Phone software updates have become a regular part of life. Apple generally issues an i Phone update several times a year.
If you don’t install them regularly when they arrive, there’s a chance an update is waiting in the wings for you to install right now, perhaps Apple’s new i Phone update for i OS 10. One of these is usually a big, feature-rich update, like i OS 10, which introduces a big update for Messages, the ability for Siri to work with apps, new ways to use 3D Touch, redesigned apps (like Maps, Photos, Apple Music, and News), and the brand-new Home app for Home Kit.
As a workaround, get the i OS 8 update by plugging your i Phone into your desktop computer and running the update via i Tunes (full step-by-step here).
That way, the update process uses your computer's much larger storage space rather than your phone's much smaller storage space.
Fixes for sync issues can range from easy to complex, but any solution will require you to take some action.