Feature nethserver 7.5 is not the same as the one in the demo

why Nethserver 7.5 display is not complete like in demo?

Not all modules are enabled/installed on the default installation, as each user has its own needs for the server(s). You can install the modules you need from Software Center. Additionaly, community modules can be installed following the instructions in the wiki.
In other words, you’ll see more elements in the menu and applications as you go on installing your modules of choice.