sql server express vs full version for a lab

[dninja at gmail.com (Robin Wood)]

Hi
I'm setting up a windows lab machine and want sql server on it. I'm
looking at playing with basic sql injection and stored procedures, in
particular xp_cmdshell. Does anyone know if there are any differences
for this kind of thing between the express version of sql server and
the paid for versions or are the differences purely in the amount of
data and things like that?

Robin