同じ。
yum upgrade は yum update –obsoletes のことだが、obsoletes オプションは標準では true なので、yum update でも yum update –obsoletes になる。
upgrade
Is the same as the update command with the --obsoletes flag set. See update for
more details.
--obsoletes
This option only has affect for an update, it enables yum´s obsoletes processing
logic. For more information see the update command above.
Configuration Option: obsoletes
update If run without any packages, update will update every currently installed pack-
age. If one or more packages or package globs are specified, Yum will only
update the listed packages. While updating packages, yum will ensure that all
dependencies are satisfied. If the packages or globs specified match to packages
which are not currently installed then update will not install them. update oper-
ates on groups, files, provides and filelists just like the "install" command.
If the main obsoletes configure option is true (default) or the --obsoletes flag
is present yum will include package obsoletes in its calculations - this makes it
better for distro-version changes, for example: upgrading from somelinux 8.0 to
somelinux 9.
Note that "update" works on installed packages first, and only if there are no
matches does it look for available packages. The difference is most noticable
when you do "update foo-1-2" which will act exactly as "update foo" if foo-1-2 is
installed. You can use the "update-to" if you’d prefer that nothing happen in the
above case.
obsoletes：旧式パッケージになっているパッケージを削除され、適切なものにアップデートされる。