"Me? Who am I but a lowly Sangheili, not knowing what is happening in There. There, what lies my peoples' future. There, where I cannot make desicions on who we fight. There, the homeworld of my people." ~ Enme Etsor
Carbine VS BR has the same pros and cons to counter each other.
Carbine : Faster rate of fire, more ammo per clip, faster reload, more accurate, one shot per fire.
Battle Rifle : Slower rate of fire, less ammo per clip ( as in shots fired ), slower rate of fire, less accurate, three shots per fire.