I assume that you mean Windows command prompt here? In that case, this thread should be moved.
You can run any programs from command prompt, not only the builtin ones. You can also to basic programming like variables, loops, conditionals and branching. The main power of CMD is the ability to run programs easily with command line parameters. This gives you huge flexibility and automation capabilities.
Yes, a batch file is basically a script for the command interpreter. The rules are slightly different though - a batch file pasted into the CMD window may not workand vice versa.