Seeing many users confused about the difference in the outputs and transactions of running
yum update versus
dnf update I feel I should explain that this is the expected result and not a bug. One reason is that DNF does not list update candidates as it explores them. More frequently however the reporter means actual difference in the proposed transaction. This is most often because the metadata the two packagers are working with were taken at a different time (DNF has a notoriously looser schedule on metadata updates to save time and bandwidth), and sometimes also because the depsolvers inside are designed to take a different course of action when encountering specific update scenario.
The bottom line is: unless a real update problem occurs (i.e. DNF refuses to update a package that Yum updates) with the same set of metadata (
dnf clean all; yum clean all), this is not an issue.