Arch Linux is an independently developed, x86-64 general purpose GNU/Linux distribution versatile enough to suit any role. Development focuses on simplicity, minimalism, and code elegance.
Ubuntu is a Linux-based operating system built on Debian's architecture and infrastructure. Ubuntu is probably the most popular Linux-based desktop operating system.
Debian is a Linux distribution composed of free and open-source software. Debian is one of the most stable and popular non-commercial Linux distribution.