When comparing YUM vs Portage, the Slant community recommends Portage for most people. In the question“What are the best Linux package managers?” Portage is ranked 2nd while YUM is ranked 15th. The most important reason people chose Portage is:
WIth portage you can decide and customize which dependencies to install through some thing called USE flags. These are keywords that when defined, will tell Portage that you want support for the chosen keyword.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Avoids dependency hell
All the metadata for installed software is stored into a XML file. This is used to avoid conflicting dependencies among packages. What's more, YUM also automatically syncs remote metadata to the local client in order to avoid failures if a command is not run at the correct interval.
Pro Simple syntax
Pro Binary delta for faster transfer times
Yum supports Delta RPMs which allow transmitting only the parts of the package that have changed.
Pro Is/was the industry standard
YUM is still widely used in corporate environments.
Pro Provides pre and post install sanity checks
What might be thought of a standard feature, isn't. Thankfully RPM provides both a transaction test and a post install verification to make sure everything installs neatly.
Pro Supports multiple verification methods
Supports verification with GPG and MD5.
Pro Clean and easy to understand
Pro Supports multiple compression methods
Supports gzip, bzip2, lzma, or xz compression.
Pro Allows for complex dependency definitions
Alongside allowing dependency on a certain package, it allows depending on a library, versioned symbol, or a GAC'd Mono assembly.
Pro Decide which dependencies to install
WIth portage you can decide and customize which dependencies to install through some thing called USE flags. These are keywords that when defined, will tell Portage that you want support for the chosen keyword.
Pro Sandboxes build process
Portage uses a sandbox as a safety measure during build processes. This is done to ensure that no packages accidentally write outside a 'safe' location.
Pro Can install multiple versions of the same package simultaneously
Slotting is a feature which allows users to install multiple versions of a software simultaneously. This is especially useful for libraries which have changed interfaces between versions.
Pro Allows both binary and source installation
With portage you can either compile packages from source or you can download and install their binary versions.
Pro Implements a standard with alternate implementations
If you need faster resolution, you can run pkgcore for search and portage for installing, and they work well together.

Pro Simple overlay management
Adding supplemental repositories, aka overlays, is easy with eselect-repository or layman.
Pro Respects customized config files
By default, portage doesn't delete or move any customized config files, thus enabling competent users to modify any config file however they want.
Pro You can view a list of programs that can be installed
With portage you can view a list of all the programs that you can install by going to /usr/portage
and running ls
.
Pro Full control over installed packages
You can fully control all packages if you use it properly.
Cons
Con Can be very slow to download headers if not on broadband
Yum can be much slower than other package managers if the internet speed is not at least average to high.
Con Slow (and might be fragile) dependency resolution
YUM dependency resolution is very slow. In addition to it, the people often experiencing very hard dependencies (it might be not a YUM problem).
Con Does fsync often
Like its successor, DNF, YUM does fsync too often. The result is poor YUM and system performance while YUM does its work.
Con Very slow overall
YUM is very slow - beginning with relatively slow startup, extremely slow default plugins, slow dependency resolution, and ending with slow installation of packages.
Con Poor design
YUM is written in Python 2 and people often blaming the quality of YUM's code.
Con High memory usage
Usually takes between 400-800MB of RSS (no problem to get over 1GB), so it's nothing for an old hardware.
Con Building from source take a lot of processing time
Most of Portage's pros are related to its "porting" process, building packages from source. This is very resource-intensive, with the few biggest packages sometimes taking even multiple hours to update or install.
Con Very slow
Dependency resolution is very slow and single-threaded, so usually you will see one of your cores running like crazy for over a minute.
Con Feature creep
It is very complicated and offers plenty of options.
Con You can not create packages under a non-portage distribution
Makes maintaining software for gentoo based systems a burden.
