When trying to install something on Linux
sudo apt update
sudo apt upgrade
That guy often appears. That is an article called "What is it?"
update Update the list of installable packages. Only the "list" is updated.
upgrade Update the installed packages. Of course, if the package list has not been updated, it cannot be updated, so it must be used together with update.
sudo apt dist-upgrade
Also the command to be. It updates packages, removes unnecessary packages, and updates the kernel. Perhaps this is more convenient than just upgrading.