It's not /that/ different after all. And from wikipedia's definition, it even fits quite nicely!

Quote:A Unix-like (sometimes referred to as UN*X or *nix) operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification.

It is not based off the original Unix, but was created to somehow replicate it and share it for free. Considering that Unix and Linux both respect and extend the POSIX standards, we can consider them to be closely related, as opposed to say, Windows, TempleOS, KiwiOS or other OS written from scratch.


Now this is all pissing in a violin, as I don't think the original Unix should still be considered to be the standard for computing.
Compared to today's computing, it was slow, had low resources and was targeted at a small elitist group that would know their shit about computing.
Computing has changed a huge lot since them, be it in terms of interface, goals or user base.
To me BSD and Linux are both following the same principles, and should learn from each others, rather than being stuck in a flame war on who's doing better at specific tasks.
They both run vi after all :P