Using GNU/Linux is by default more secure than using Microsoft Windows, this is common knowledge; however just because you use GNU/Linux, does not mean that your system is secure, and that is why some distributions have been created in order to maximize security; such as QubesOS.
QubesOS is very different from your typical run of the mill distro, such as Ubuntu or even the more hardcore like Arch Linux and Gentoo. QubesOS runs multiple virtual machines linked together under a single user-interface, to form a container based / compartmentalized operating system.