The most complete answer came from Alexey Demin, corporate sales manager of G Data Software in Russia and CIS.
1. The popularity of Windows systems on a desktop is much higher than that of Linux which is much more often used on servers.
2. By default, the Linux user works under an unprivileged user. Administrative access (root) to edit system files is provided only for system configuration, etc. An ordinary user has the right to read absolutely for all system files, which prevents viruses running on his behalf from intercepting the system control.
3. Linux has a different access rights subsystem, it does not have a registry and the settings of all programs are stored in the /etc directory where the normal user has read-only access. In Windows many programs just need write access to the system areas for normal operation. In other words, the Linux user (read: virus) cannot change either byte or in any file.
4. If even a normal user runs some malicious program which, for example, deletes all the data, the maximum that will happen is to delete the data in the user’s home directory. The system itself cannot be affected in principle. The user can run some malicious code that will start some service on some TCP port or will connect to some host on the Internet to transfer data. After rebooting, this malicious service does not start itself. It is impossible to make changes in the system boot scripts. This technique is very often used by “malware”.
5. Users of GNU\Linux on a desktop, and even more so on servers, have a higher competence. This allows them to monitor the system more qualitatively.
6. GNU\Linux has a powerful firewall, which is part of the system itself. If set up correctly, security is significantly improved.
7. No program can be launched by itself, which is an important point in the security of GNU\Linux systems.