what are similarities and differences between linux and unix?
Because Linux evolved from UNIX, but Windows evolved from DOS.
There is very little difference in the C compiler between Unix and Linux; in some cases (the gcc compiler) it is the same. The differences come in when using system calls; some system calls do not exist in Unix or Linux, although most do. The program I work on compiles the same way (for the most part) between all commercial versions of Unix and several variants of Linux. In other words, the code is fairly portable across platforms.
Since there isn't a UNIX 95 or UNIX 98 per se, I think you are referring to Windows 95 or Windows 98..
Windows, Linux, Ubuntu, Linux Mint, the list is huge!
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.
Windows, Linux and UNIX machines
Windows, Linux, Unix.
unix is a multiuser operating system but widows is a single user operating system.
Unix and windows are two separate groups of operating systems. Windows is the operating system of about 90% of personal computers, while unix is the basis of many other operating systems, such as Mac OS X
autosys
Unix, Linux, windows and compilers etc.
To put it very generically, Linux is an operating system kernel, and UNIX is a certification for operating systems. The UNIX standard evolved from the original Unix system developed at Bell Labs. After Unix System V, it ceased to be developed as a single operating system, and was instead developed by various competing companies, such as Solaris (from Sun Microsystems), AIX (from IBM), HP-UX (from Hewlett-Packard), and IRIX (from Silicon Graphics). UNIX is a specification for baseline interoperability between these systems, even though there are many major architectural differences between them. Linux has never been certified as being a version of UNIX, so it is described as being "Unix-like." A comprehensive list of differences between Linux and "UNIX" isn't possible, because there are several completely different "UNIX" systems.