NuTyX Linux

NuTyX Linux is not an immutable distribution. 
NuTyX is a flexible, independent Linux distribution designed for intermediate to advanced users, based on Linux From Scratch (LFS) and Beyond Linux From Scratch (BLFS). 
Key details about NuTyX include:

    Mutable System: Unlike immutable distributions (like Fedora Silverblue or MicroOS) that use read-only filesystems, NuTyX allows users to modify the base system, following a traditional, mutable approach.
    Package Management: It uses its own custom package manager called cards.
    Flexibility: Users can install individual binary packages, groups of related packages, or compile source packages via its ports system.
    Init System: It supports sysvinit, and is known for allowing flexibility in init systems. 

Immutable distributions, examples include Fedora Silverblue, openSUSE MicroOS, and Vanilla OS.

Nitrux Linux

Nitrux Linux is an immutable distribution, featuring a read-only root filesystem to enhance security, stability, and reduce system-level, accidental, or malicious modifications. It utilizes NX Overlayroot to manage the read-only state, along with the Nitrux Update Tool System (NUTS) for atomic, safe updates. 
Key aspects of Nitrux's immutability:

    Immutable Root: The base system cannot be modified by users or applications, making it more resilient.
    Atomic Updates: Updates are applied as a complete image (all or nothing), allowing for easy rollbacks if an update causes issues.
    Application Management: Instead of apt to install system software, Nitrux encourages the use of AppImages, Flatpaks, and its own AppBox to manage user-space applications.
    Hybrid Approach: While the core is immutable, it is based on Debian Unstable (Sid), providing access to cutting-edge software within a controlled, safe environment. 

Nitrux has transitioned to this model to offer a more secure and robust desktop experience, often utilizing the Hyprland window manager in its recent releases.