For the most part, every Unix-based and Unix-like (and by extension, Linux) distribution will have a root account (equivalent to a system administrator account in Windows). The remaining accounts will be allocated for the users and for certain applications.
Linux is an open system, Unix is not.
"System Administrator" is just that a general sysadmin that more than likely is only certified to use Windows Server and is network-savvy. Whereas a Linux System Administrator is certified in Linux and networking.
Systems Administrator :)
Linux is a Unix-like system. This means that it is inspired or influenced by Unix in some shape or form (Linux started off from Minix), but it is not directly derived from Unix. However, BSD is based on Unix, and macOS is indirectly Unix-based because of its mixed heritage with BSD.
Unix came first; Linux is a clone of the Unix Operating System.
unix
With most Unix-derived systems, "root" is the super-user account.
Linux is not an exact copy of any previous operating system. It is modeled after various Unix and Unix-like systems.
No, but Linux is based on Unix since Linux is a Unix clone.
Linux is far more common these days than traditional Unix. But as any old system administrator will tell you, learn to learn, don't learn the system. There are numerous differences between the different Linux distros, differences between Linux and Unix, and differences between each of the Unices. Learning everything about each system is a daunting task, and probably near impossible. Rather than, say, learning all of the different command line switches for "ls" on each system, just know how to access a man page.
Linux.