I found an article on your question, i think it will solve all your problem.
Many a times we get confused with Unix and Linux also threat them as synonyms but that is not true. UNIX is copyrighted name only few of the companies are allowed it i.e. IBM AIX and Sun Solaris and HP-UX. This quote from Official Linux kernel README file confuses most:
Linux is a Unix clone written from scratch by Linus Torvalds with assistance from a loosely-knit team of hackers across the Net. It aims towards POSIX compliance.
In this article I am trying to describe the various differences between Unix and Linux under the following headings -
- Future OS
UNIX was created in the 1960s by the AT&T Bell Labs (Ken Thompson and Dennis Ritchie) and first commercially UNIX OS became available in 1970. First release of Unix was having a command line interpreter and some small utility programs with future extension for the multitasking and UNIX evolved from there.
In 1991, Linus Torvalds began working on a UNIX like OS known as Minix. The Minix source code was freely available under GNU GPL and he successfully modified this code for use on x86 PC systems. By September 1991, Torvalds has successfully completed the first Linux kernel designed for PCs. This kernel included various system utilities and libraries from the GNU project to create a usable operating system based completely on open source code.
The original source of this article is http://tech.queryhome.com/47860/comparison-between-linux-and-unix-operating-system