General :: Difference Between Cron And Command Line Environment?

so i have a few shell scripts that execute wonderfully when i type them at the command line but they fail when they are run from cron.

for example, if i run a script from command line that contains

Code:
shopt -s nullglob

to prevent problems with for f in *.mp4 type loops, it works fine from terminal command line but when called from cron, it gives an error->

Code:
/home/centralsqwall/Videos/videochecker.sh: 91: shopt: not found

a couple other random errors as well...

so there is some difference in the shell from cron and the terminal?

i'm running ubuntu 9.10, #!/bin/bash

what are the commands i should be using to echo my environment or simulate cron environment from the terminal?