The main difference between Unix and Linux is that Unix is a family of proprietary operating systems, while Linux is an open-source operating system based on Unix principles. Both systems are similar in structure and design, but they have some key differences.

Unix:

1. Unix is a family of operating systems developed in the 1970s at AT&T Bell Labs. Unix is proprietary software, meaning its use and modification are limited by licenses and ownership rights.
2. Unix has served as the foundation for many commercial operating systems, such as Solaris, AIX, HP-UX, and others.
3. Unix is primarily used on servers, workstations, and in the infrastructure of corporate networks. Unix is generally a stable, reliable, and secure option for a business environment.

Linux:

1. Linux is an open-source operating system based on the Linux kernel, created by Linus Torvalds in 1991. Linux was developed using Unix principles, but it is a free and open alternative, allowing developers to modify it according to their needs.
2. Linux has numerous distributions, such as Ubuntu, Fedora, Debian, CentOS, and others, each with its own focus and specialization. Some distributions are designed for servers, while others are for desktop computers, mobile devices, and so on.
3. Linux is widely used on servers, desktop computers, mobile devices, embedded systems, and supercomputers. It is a popular choice among developers and users due to its flexibility, stability, security, and community support.