Just came back here to find answers!
SAHM, I use it as a rice/pasta substitute. No real "reason" that I can think of other than it's a little something different than the usual.
As for the differences... Regular couscous (usually sold in white "rice-o-roni" sized boxes from the Near East company would be about the size of spaghetti noodles cut as long as they are thick (if that makes sense) Israeli couscous is larger, maybe the size of BB's and has more of a "pasta" feel to it, while the other is more "grain/rice" like