iTunes says an update is available but iPhone doesn't (iOS 10.1.1)
Answer from this MacRumors article: http://www.macrumors.com/2016/11/09/apple-releases-new-version-of-ios-10-1-1/


  Apple today seeded a minor version change to iOS 10.1.1, the current
  version of the iOS 10 operating system. The update is minor enough
  that it did not warrant a full 10.x.x number change, but it does
  include an updated build number. 
  
  iOS 10.1.1 being released today has a build number of 14B150, while
  the initial iOS 10.1.1 release, which came on October 31, had a build
  number of 14B100.
  
  The new build of iOS 10.1.1 is only available as a download from
  Apple's servers and cannot be obtained over-the-air at this time for
  those who have already installed the first version of iOS 10.1.1. The
  new version of iOS 10.1.1 will likely be provided to those who have
  yet to install iOS 10.1.1, as it otherwise requires an iTunes
  connection to obtain.


In other words, you can safely update via iTunes to benefit from this minor update.