Most of us think that Linux was created as a response to Windows which is the most popular operating system nowadays, but it is actually a response to UNIX. UNIX is a very old operating system that was intended to operate on large computers and mainframes. It is not cheap or easy to use, that is why only a very few people use it. Linux, which is developed by Linus Torvalds, is based on the UNIX system but does away with the complex mechanisms that make learning UNIX very steep.
Being the predecessor of most of the operating systems that is being used today, UNIX has existed for a very long time and has changed very little since it was created as a processing machine and very little processing power was used towards better interfaces and ease of use improvements. Linux was built with the common user in mind, therefore most Linux distributions provide users with a very capable GUI that also eats up a portion of the computer’s processing power. Owing to Linux’s flexibility, the GUI can be removed for server applications that don’t need fancy GUIs.
It was developed to maximize the productivity of high end computers that are used by big companies, and all of the releases for UNIX are built with the latest high end hardware in mind and it is not usable in the common desktop computer. Linux, on the other hand, can scale reliably across different hardware platforms making it a good choice for most people.
There is also the cost of these two operating systems. Linux is a free OS that is developed by the community and licensed under the GNU GPL. Unix, on the other hand, is a proprietary software and you would need to buy it if you want to use it.