Technical Analysys of Linux Distributions Shared Software

GNU BASE Software
Linux is much more than Linus Torvalds' kernel: it's a full featured multi purpose operating systems which integrates many basic utilities from the GNU project.
These utilities cover the main system need and are GPL re implementations of basic Unix commands and tools:

Glibc GNU C Library is one of the most important components of most modern Linux distributions. It is used by almost all C programs and provides the most essential program interface.
Bash Bash is an sh-compatible shell that incorporates useful features from the Korn shell (ksh) and C shell (csh). It is intended to conform to the IEEE POSIX P1003.2/ISO 9945.2 Shell and Tools standard.
Gcc The GNU Compiler Collection is a full-featured ANSI C compiler with support for K&R C, as well as C++, Objective C, Java, and Fortran.
Coreutils Collection of basic file, shell and text manipulation utilities. Combination of file (fileutils), shell (shellutils) and text (textutils) packages into a single release.
File Utils Used to handle files: chgrp, chown, chmod, cp, dd, df, dir, dircolors, du, install, ln, ls, mkdir, mkfifo, mknod, mv, rm, rmdir, sync, touch, vdir.
Shell Utils Common shell utility programs: basename, chroot, date, dirname, echo, env, expr, factor, false, groups, hostname, id, logname, nice, nohup, pathchk, pinky, printenv, printf, pwd, seq, sleep, stty, su, tee, test, true, tty, uname, uptime, users, who, whoami, yes.
Textutils Text utilities: cat, cksum, comm, csplit, cut, expand, fmt, fold, head, join, md5sum, nl, od, paste, ptx, pr, sort, split, sum, tac, tail, tr, tsort, unexpand, uniq, wc.
Inetutils Collection of common network programs: ftp, ftpd, rcp, rexec, rlogin, rlogind, rsh, rshd, syslog, syslogd, talk, talkd, telnet, telnetd, tftp, tftpd, and uucpd.
Make Generates executables and other non-source programs. Make reads a file called a 'makefile' to learn how the files in your program are put together.
tar - gzip Creates tar archives - Compresses and decompresses files.
vim - emacs Two powerful and largely used text editors.
Gnu and OpenSource Software
Besides the basic libraries, programs and command line tools every Linux distro provides common and notorious software for different uses (desktop and server). The code, the sintax of its configuration files and its working logic are always the same, but different distro can provide different versions, place files in different positions, integrate in the whole system and different ways. Here are some very common and used programs:
XFree86 An OpenSource X server, necessary for a graphical environment in Linux
Gnome GNU Network Object Model Environment. An integrated desktop and applications framework
KDE The Big Alternative to Gnome: An integrated graphical desktop environment
OpenOffice The most famous, advanced and mature Open Source Office application
Perl A programming language largely used for scripts, programs and web applications. Usually available with various libraries for different uses.
Apache The most used and powerful Web Server software
Sendmail / Postfix Two of the most used Mail Delivery Agents. Often both are presented as alternatives that the user can choose.
Bind The most used open source DNS server implemention.
Samba The open source implementation of a CIFS/SMB file server
Gimp The most advanced and know graphic images processing and manipulation tool.
Mozilla One of the most advanced and known opensource web browsers.