Hey,
A CB radio is a much more limited radio, bu the good thing about it is its much simpler, you have 40 channels, and you need not take a test to get a license. you dont need to learn a new language, and its fun.
Ham radio is a much more complicated radio which you can generally talk MUCH further, (world wide) but you need a license for it, you need to take a test and pay some small fees. you can talk much further, and can almost always find Someone to talk too, from who knows where!
CB radio i enjoy because as you are driving down the road you know your talking to people around you. (sometimes during the day you wish you wouldn't though) it can be crude and rude,
if you wanna get a GREAT mix between the two Try getting a CB Radio with SideBand also known as SSB (single side band) Galaxy makes the "Galaxy DX949 and 959" that are pretty decent side band talkers and a lot of radio technicians know their way around the galaxy.
Side Band allows you to talk much further than the standard CB
A legal CB can put out 4watts. An AM signal is made up of three parts, an upper and a lower band and the AM carrier. to get your 4w out your radio is actually putting 12w out, but on sideband you are only using 1 out of the three so legally you can use all 12watts on sideband allowing you to talk further. Sideband takes a little playing with to get used too, a lot of the time you will find people talking on channels 35 to 40 on sideband.
if you were to get your radio "illegally tuned and tweaked" you can get more power out (normally 30w with a galaxy) which allows you to talk even further, generally you can talk in a good 100m radius from a good mobile set up, or even further from a base station. If the skip is rolling in, i have talked to florida and alaska from New York.
but... these distances and power do not compare at all to a ham radio... but its a good starter anyway. i enjoy it.
hope thats not too much boring confusing info :-/ Hope it helped.