- Arch Linux supports only x86_64 in the main project
- Void supports i686, x86_64, armv6, armv7 and aarch64 with both musl and glibc under one project, one source repository.
- Arch linux does not allow partial updates
- Void linux allows partial updates because the package manager tracks shared libraries and big issues can be avoided by aborting the transaction if a conflict exists
- Arch puts everything into one big package
- Void splits packages, not as much as debian, but at least the development stuff is in a `-devel` subpackage. This reduces the installation size by alot (especially useful for embedded systems, arm...).
- Arch has no repository with debugging symbols
- Void has a repository with -dbg packages containing the debug symbols.
- Arch only maintains two kernels, mainline and lts.
- Void maintains kernels in packages with the a version suffix, `linuxX.XX`. Users can choose which series for how long they want to use. (also great for embedded systems)
- Arch kernel updates remove the old kernel version
- Void keeps the old kernels, the administrators can boot the previous kernel until they decides to purge old kernels with the `vkpurge` script if new kernels work fine.
This are the differences on top of my head, there are plenty more.
But yes tell people they waste resources.