Okay, seems I have been wrong or have misunderstood the complexity of the app. I always understood it was an additional app and another one, but some more research led me to see, that once Server.app is installed, Mac OS X is identified as "Mac OS X Server Lion".OSX lion Server is a full fledged operating system. Its OSX with additional services, and applications needed for a server implementation. Many (all?) of the core components are OSX server is identical to OSX, its what apple adds to the OS that makes it more specialized
Straight answer: No, it's not a standalone operating system. It's a package that you install on top of an existing Lion installation that adds various severs, tools and utilities. Many of these are just configuration utilities for server facilities already built into Lion (e.g. Apache and the email server) but there is some extra software as well. You are also given an option to "tune" various system settings to optimise your system for server, rather than desktop, use.Is OS X Lion Server an app that runs on lion or a standalone operating system?