If im not mistaken the larger the ratio the taller the teeth on the ring. The higher numbers like 5.56 are more for low end torque crawling and mud bogging. Look into your jeeps statistics a little more to see if you have the 3.73 rear end. Not sure if all of them came like that. 3.73 is a perfect in between gear.
..thats the relationship between turns of the driveshaft to the turns of the differential.
As lower the number, as faster the wheels turn (Low engine revs on high speeds) high numbers are preferable if you need lots of torque (offroading). High engine revs with slow spinning wheels: lots of power