As was mentioned earlier, the complete Linux system contains hundreds of utilities and lots of applications. There are also libraries, documentations, modules, etc. From now on we will refer to them as components . Most such components contain multiple files. All the distributions pack these files into a single file, known as a package.
Packaging allows for easy installation and upgrade.
If package A utilizes or depends upon package B and you wanted to remove package B or upgrade it in a way that breaks package A, the system will warn you. Thus you can easily upgrade components of an rpm or deb system without knowing their interrelations. The startup or boot-up procedure of distributions also differ somewhat. If you come from the DOS world you know it reads config.sys and autoexec.bat at boot-up, they set some configurations and run some commands. The structure of this directory differs.