Men's jeans--and other finished bottom men's pants--are usually sized with the the waist size first, then the length, expressed as the inseam of the pants. However, if you're looking at pants that say 30R, they are 30 Regular, meaning that they have a 30" waist and a regular rise, and regular length. "Regular" rise in pants are cut for men anywhere from about 5'8" to about 6'0". The 32L are long rise, meaning that they are for men from about 6'1" to about 6'4". The inseam on the regular pants are probably 32", and the inseam on the long pants are probably 34".
I'm a manager at a men's wear store.