Update or Upgrade?
An upgrade is the change of the main version of software: e.g. from QuarkXPress 2017 to QuarkXPress 2018 or from macOS El Capitan to macOS Sierra.
Upgrades are usually subject to a fee.
An upgrade is the change within a major version of software: e.g. from QuarkXPress 2016 sub-version 13.1 to 13.2. If only the third or fourth position changes, one also speaks of service updates: e.g. from 9.5.4 to 126.96.36.199.