Barrage Fire with Monster Ribults?

What's the difference between normal and barrage fire with the monster ribult?

Barrage fires longer and takes longer to reload.

Barrage is quite excellent if the enemy starts bunching up. A timed Barrage fire can cause a wide-scale rout as far as i've seen, but could also be useless if the conditions aren't nearly perfect.

And its invaluable when being charged by cavalry. Its better to shoot lot of bullets wwitht reloading when cavalry is geting close than spend some of this time reloading. After barage is completed, run away and let melee units deal with cav.