Kar is an abbreviation of 'Karabiner' which is german for carbine, and a carbine is a shorter barrel (usually heavier barrel) than its full length counter part.
So the Kar98 is a carbine.
The kar98K is a shorter version of that carbine ( the 'K' standing for kurz, which is 'short' in german )
That is my understanding as well (based on wiki ) ...which is the reason why I am confused about the weapon profiles in the patchnotes, i.e. G43 (being a longer rifle afaik) having a carabine weapon profile and kar98 (being shorter rifle) not.
As someone suggested above, maybe Relic uses the term carabine in a different meaning, not the actual definition (??).