Manjaro Linux is not Arch Linux in the pure sense — but yes, it is based on Arch underpinnings and Arch principles. Nor is using Manjaro Linux the same as using pure Arch or more direct derivatives.
Its independence breaks away from the pure Arch mold. It puts a user-friendly face on an Arch-based distro and gives you a choice of sensible and productive desktop interfaces and features. Manjaro’s user base targets newcomers, not the more technically inclined experienced Linux user.