2.94 open gears

I found a rear-end for sale today with 2.94 open gears. What is the difference between that and the 3.23 gears that I see. I'm still trying to learn the rear-ends here, and im still confused on gear ratios and such. How would the ride be different between the gear sets? going into a 68 dart with a 318. Thanks!

-Nick
Author: 68Dart