to answer your question KDE is not arch. Linux has a bunch of distros, you can think of one as a collection of packages. some distros want to do things one way some want to do it others.

the biggest difference between distros for most users are mostly desktop environments and package managers. KDE is the desktop enrollment, there are many others that you could also use, like gnome, or use none at all and only use the terminal. the package manager is how you get new packages and update the ones you already have. examples are apt and pacman.

you can make any distro work like another by installing the same packages, although this may not always be the easiest to do. an easy way to change your experience with Linux is to try a different desktop environment, you can run multiple on the same distro and switch between them, see what you like.