When the Windows was launched some 20 plus years ago, it caught like wild fire because it was all of a sudden so easy to use and so convenient to install. The best things that it maintained a constant identity as the product of Windows, while on the other hand Linux went along under many names, such as Knoppix, Mandrake, SuSe, Windows, and so on. With each name (different companies) Linux as an operating system had slight variations. Hence, it was bothersome for people to keep track, and sometime use Linux due to this aspect.

Then comes the inherent difference between these operation systems.

Technically speaking, you will find the GUI is optional in the Linux

operations system while it is part and parcel of the Windows. The separation of the GUI directly affects the reliability and speed not to mention efficiency of a server and hence here Linux scores over the Windows.

Another major difference is in the way these operating systems handle their command prompts. While Windows uses similar command interpreters for its Windows 9x versions, the NT series have a different style but common to each other. Linux on the other hand, being a UNIX version has the capability of handling multiple command interpreters, which can be a boon, though it mostly favors Bourne Again Shell (BASH). The other interpreters that you will find in Linux are C Shell, ash, Korn shell and so on.
The best and most highlighted difference is the price tag attached to the operating systems. Windows is an expensive to say the least, operating system which comes with a copyrighted license, while Linux is free for all, easily downloadable anytime you want it. The downside here is that Linux has instruction which will tell you what to do which may be why people are indeed reluctant to move away from Windows; though there are a few low cost Linux versions which come with automation and manuals.
Another plus in favor of Linux is the lack of any security requirement. The viruses, spy wares, malawares and what not you have it are all a product of Microsoft, for Windows. Hence, while you have to use high security firewalls with Windows, you are free from any such headaches with Linux.

Lastly, you have the difference of availability of software. The majority of the software that you find on the market are for Windows and they will not run on Linux unless Windows is somewhere configured as a subsystem which actually goes against the reason of using Linux in the first place.

Hence, till a suitable interface is found where Linux can be compatible with Windows without using Windows itself, have a few clear-cut instructions for first time users and sufficient information on its technicalities, people will prefer Windows to Linux, even if they have to pay to use it.