sudo apt-get upgrade: Does not have a significant impact on the system and can be run at any time.
sudo apt-get Dist-upgrade: involves the core of the upgrade, usually has a real impact on the system functions, may be required to uninstall some installed software may also install some additional software, usually should be cautious operation, especially with unfinished work, However, you should try to upgrade as much as you allow, and you should be able to involve some major core upgrades, such as security.
Dist-upgrade'll perform updates to software, makes actual changes to the system and can has an impact on the fun Ctionality of your system. Using Ubuntu, a dist-upgrade often involves kernel upgrades. Kernel upgrades can really change things, especially if you have manually installed proprietary drivers. If you were currently working on a project for school or work, it's best-wait until the project is finished before perf Orming a dist-upgrade. You can safely perform an upgrade at any time and it is not having a large impact on system functionality. You should, however, perform a dist-upgrade whenever possible as there is often security updates for the kernel. Also, a dist-upgrade may uninstall existing packages or install extra packages where an upgrade would not.
Upgrade upgrade is used to install the newest versions of all packages currently installed on the system from the sour CES enumerated in/etc/apt/sources.list. Packages currently installed with new versions available is retrieved and upgraded; Under no circumstances is currently installed packages removed, or packages not already installed retrieved and Insta Lled. New versions of currently installed packages that cannot be upgraded without changing the install status of another PA Ckage'll is left at their current version. An update must is performed first so, Apt-get knows that new versions of packages is Available.dist-upgrade dist- Upgrade in addition to performing the function of upgrade, also intelligently handles changing dependencies with new ver Sions of packages; Apt-get has a "smart" conflict resolution system, and it'll attempt to upgrade the very important packages at the EX Pense of less important ones if necessary. So, Dist-upgrade CoMmand may remove some packages. The/etc/apt/sources.list file contains a list of locations from which to retrieve desired the package files. See also Apt_preferences (5) for a mechanism for overriding the general settings for individual packages.
Ref:https://www.quora.com/what-does-command-sudo-apt-get-dist-upgrade
Ref:https://askubuntu.com/questions/81585/what-is-dist-upgrade-and-why-does-it-upgrade-more-than-upgrade
Ubuntu sudo apt-get upgrade and sudo apt-get dist-upgrade differences