Winding up ....... !
You can look at 'Advanced Bash-Scripting Guide
' to get a better understanding of 'BASH'
As for comparing 'DOS' with 'BASH' you would be looking at a comparison of say a MACK truck and a VW. The VW will get you there uncomfortably and rather slowly but the MACK will let you move your house with you as long as you know how to use the proper equipment.
'DOS' is DISK Operating System where 'BASH' is Bourne Again Shell which is used to provide the means for a user to perform action(s) on system.
I suggest that you do some searches here on LQ and then Google as this very subject has been covered many times.