Linux vs Unix is not the same thing. Linux is a kernel, a core of an operating system that needs a package to be complete. There are plenty of Linux distros that, together with additional elements, make Linux an entire OS. On the other hand, you have Unix, an older and complete OS that has changed significantly over time. Now there are billions of devices with a version of Linux (computers, Android smartphones, embedded devices, etc.) and billions of gadgets with Unix (Mac computers, iPads, servers and more).
History of Unix
As we mention, Unix is older than Linux. There was a developing team of the company AT&T Bell Labs with the goal of having an operating system for PDP-7. The leaders of the team were Ken Thompson and Dennis Ritchie. The original concept was borrowing ideas from its predecessor Multics, but it was written from scratch in the C language. This made it portable to other devices, which was incredible at the time. The development started in the late 60s. In 1971 it was first published inside the company, and in 1973 it went public.
It grew fast, and AT&T Bell Labs started selling licenses to other companies.
In the late 70s, the University of California, Berkeley started using it and developed its version BSD (Berkeley Software Distribution). The version became popular, and it gave birth to open-source versions of it like FreeBSD and OpenBSD.
There were various versions of Unix, and a standard was needed to establish what is a true Unix. The standard was called POSIX and was created in 1988 and is currently managed by the Open Group.
Some of the popular versions were HP-UX, AIX (IBM), Solaris, and Xenix.
The current macOS is based on the BSD version of Unix and technically is a Unix OS.
History of Linux
Linux came to a lot later. Its creator Linus Torvalds started it as a university thesis. The first version was using GNU and a brand new kernel (Linux). In the development, Linus used a lot of ideas from MINIX and BSD-based OSes. Linux was developed and still is open-source. People can see the source code and edit it the way they like. This is the reason now there are plenty of distros.
If you find yourself more interested in how it all started, you could check the following article about Linux History.
Linux vs Unix differences (comparison)
|Examples||Mint, Ubuntu, Debian, Fedora, CentOS, Android, Arch Linux, and more.||macOS, OS X, Solaris, BSD, FreeBSD, OpenBSD, and more.|
|Development||Mostly open-source community development. Each distribution of Linux has its own community. Behind some of the distros, there are companies that develop them.||Original Unix was developed by AT&T and now there are various companies that develop their version. There are open-source versions that are community-driven.|
|Cost||Mostly free, some distros are paid||Mostly paid, some versions are free.|
|GUI||There are two main desktop environments (DE) – Gnome and KDE. There are additional DEs like Cinnamon, Mate, LXDE, Xfce, and more.||Originally Unix used command-line interface, then moved to Common Desktop Environment. Now many versions use Gnome.|
|Usage||Servers, desktops, laptops, tablets, embedded devices, video game consoles, and more.||Servers, desktops, laptops, tablets, mobile, video game consoles, and more.|
|Default Shell||Bash originally, but now there are others like Dash, Sh, Zsh,||Bash originally, now many use Zsh, KornShell|
|Supported file formats||FAT32, , FAT, NTFS, Ext2, Ext3, Ext4, Jfs, ReiserFS, Xfs, Btrfs||jfs, gpfs, hfs, hfs+, ufs, xfs, zfs|
|Viruses||Around 100 known viruses that are not active now||Round 120 known viruses that are not active now|
|Availability||Free open-source mostly. A few distros are paid.||Mostly paid license. A few variations based on Unix are free (BSD derivatives).|
The biggest difference between the two is that Linux is a kernel while Unix is a whole operating system. There are different distros of Linux that use its kernel and become a whole OS. Now both are very popular and both have different distros. There is not one single best distro. It strongly depends on your needs.