1. Apache is a company name, the other 3 are Operating Systems
2. apache is not a operating system
3. Linux, DOS, and Unix are all Operating Systems,
   Apache is a Linux Web Server.
4. apache I think I studied as level ict 2 years ago x
5. Apache is a web Server but many people also argue that Linux is not as OS, it's a kernel that's used in a desktop operating system (like Ubuntu, Fedora etc).
6. apache is a server name used by companies, not an operating system
7. One is a rather fearsome Indian tribe or a very capable Attack Helicopter depending on your standpoint… Linux - wasn't he in Snoopy?
8. apache is not an operating system
9. apache!
10. Apache (it's a web server).

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