I'm not quite sure about what it is you want the sprite instances to do differently, but I'll take a crack!
If you just want two or three identical sprites to behave differently, you can use their unique IDs to select them to tell them what to do.
You can use instance variables in your sprite object, so you could check that to see what the object should "do". Like:
If Cat.Sleeping, do nothing. If Cat.Meowing, meow; and so forth.
That is just for boolean instance variables you create. You can make number variables and text variables as well, so you could theoretically make:
Check out the man page here =) I'd Link it, but I'm a potential spammer, so they don't let me post links.. yet. mwahahah.