Well the most obvious difference is package management. Aside from that
you can always add GNU utilities to Solaris and FreeBSD so that the
differences from a user perspective can be quite small.
thanks for your response, but i am asking in server perspective. not GUI.
in my opinion Ubuntu/Debian are the best in GUI's however i am more interested to know about server side think,
for example. samba, postfix, storage stuff, ftp,ssh,http,smb,nfs, etc and all other things can be achieved in both freebsd and Debian and even in solaris.
ok lets forget about solaris due to proprietary in nature. lets talk about opensolaris (illumos) openindiana, omniOS they are also very very stable.