Q:

what is the difference between Linux and Unix "in general" and "command-line"?

if anyone can Summarized the difference between Linux and Unix in general and in command-line in particular

A:

Licences differ from GPL (Linux) to BSD (*BSD variants) to some other (whatever licences Solaris, HP-UX etc use)
Kernel differs.
System libraries differs; Linux distributions tend to use GNU userland, BSD, Solaris has their own. In my opinion for example FreeBSD feels much more like a finished product with more comprehensive and up-to-date documentation and system tools written for it, whereas Linux distributions are more like a puzzle where every piece is fetched from a different source. Linux works fine and is a nice system, though. :-)
Package management differs, but that can be said between Linux distributions, too.

Other than that they are pretty much the same. Apache, MySQL, and all the other common software can be run on all of them.

