Hi!
Recently, I have migrated from Manjaro to Tumbleweed, as some things made me reconsider my daily driver distro ^^’ I’m still new to OpenSUSE, so please bear with me 
So… I noticed that I receive frequent updates via KDE Discover and not as much via Zypper. I have Packman and Opi installed. The questions is:
What’s the deal with 2 software update channels? Should I use only one of them, or maybe both?
I’ll be grateful if someone will enlighten me on this matter ^^
Discover belongs to KDE/Plasma. Zypper belongs to the operating system. So does YaST. They’re both built and maintained by SUSE. Zypper is the only package tool I use except during system installation, where YaST is the only option. Opi is best for searching for packages not available in currently configured repos. Packman is a package source, not a manager.
Stick with zypper always does the best. Opi will search for packages that have been built from the obs and will then automatically invoke zypper to carry out the required steps for their installation. The packages available on obs can be likened to those found on Arch’s AUR (Arch User Repository).
For my TW install, I run ‘zypper dup’ …
For my MicroOS Kalpa install, I run Discover.
For TW, I have only used Discover to install a application Flatpak.
Ok, I found the answer myself 
There is no disparity. The number of proposed updates is the same either using zypper or KDE Discover