Different type of shell to declare

#!/usr/bin/sh      OR      #!/bin/sh               Declares a Bourne shell
#!/usr/bin/ksh    OR      #!/bin/ksh            Declares a Korn shell
#!/usr/bin/csh    OR      #!/bin/csh             Declares a C shell
#!/usr/bin/bash  OR     #!/bin/bash          Declares a Bourne-Again shell