FRS uses different frequencies than CB, and is limited to 0.5 watt (basically a "walkie-talkie"). I have been with groups that use FRS and for yakking in a tight convoy they work okay. They are fine for transmitting 100 yards or so but cannot be relied on for more than that.

CB is limited to 4 watts and so has greater range than FRS, maybe 5 miles depending on terrain.

My local Midwest Overland group has gone to 2-meter (VHF) ham radio for greater range than CB, running 55-75 watts can reach out 15-20 miles depending on terrain, but that doesn't do you any good unless the guy on the other end has one too.

So in the end it comes down to whatever everybody can agree to use, unfortunately none are compatible with the other and it is actually illegal to make a radio that does more than one type. As a result I carry 3 kinds of radio in my Trooper

The Moab group uses CB.