1. Package Management: NixOS uses the Nix package manager, which enables atomic upgrades and rollbacks, making system upgrades more reliable. openSUSE, on the other hand, utilizes the Zypper package manager, which follows a more traditional package management approach.

2. Configuration Management: NixOS employs a declarative approach to system configuration using the Nix language, allowing for reproducibility and consistency across systems. openSUSE utilizes the YaST configuration tool, which provides a more interactive and traditional way of configuring the system.

3. Rolling Release vs. Fixed Release: NixOS is a rolling release distribution, meaning that users receive updates frequently and continuously without the need for a complete system upgrade. openSUSE follows a fixed release model, with periodic major releases that introduce significant changes.

4. Infrastructure Management: NixOS focuses on providing infrastructure as code, allowing users to define system configurations in a reproducible and concise manner. openSUSE, although capable of system configuration management, doesn't emphasize infrastructure as code to the same extent as NixOS.

5. Community and Support: NixOS has a more niche community due to its unique approach, but it offers extensive support for functional programming enthusiasts and developers interested in declarative system configurations. openSUSE has a larger and more diverse community, providing varied support options and resources for users with different backgrounds.

6. Philosophy and Design: NixOS is designed around the principles of functional programming and immutable infrastructure, emphasizing reproducibility and control over system configurations. openSUSE, while versatile and flexible, has a more traditional design approach that caters to a wider audience with different preferences and use cases.

In Summary, NixOS and openSUSE differ in package management, configuration management, release models, infrastructure management, community support, and design philosophy.