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).