No, no.
Yes, Yes...
"Zypper dup" was designed for Factory use right from the start, back around 2008, for "daily" use. Each instance of Factory is in fact a new release: some packages are updated, some downgraded, some disappear. Not every day, true: when they don't, you can use "zypper up".
Dup was designed as 'distribution upgrade' - the official way to move from openSUSE stable M to openSUSE Stable N
Old Tumbleweed required dup because it was a derivative of factory.
Sory, Carlos.. no, the old TW was in no way linked to Factory.. it was a repository adding packages that have been proven stable in Factory (which is the only 'link' it had) into an add-on repository targeting a stable release...
The New Tumbleweed requires dup because it is Factory. A name symlink, if you prefer.
No Carlos... not obejction that TW is Factory (i know that very well,
if you follow this list carefully)... but as there are no vendor
changes to take into account (unlike in the old TW setup), there is
basically no difference nowadays between up and dup... if you feel more
comfortable typing dup, do so.. but stop confusing 'the new users' with
old wisdom please.
--
Dimstar / Dominique Leuenberger