Well, UV method is probably the most accurate, you can get the smallest traces.
Basically, the toner transfer is when you print the circuit on a piece of photopaper, then iron it to the board so that the toner sticks to the board. The toner protects teh copper from the etchant, resulting in traces only where the etchant is.
The UV method (ive never done it) is where you print the circuit on a transparent sheet, and then place it over the board. then expose the board to UV light with the transparent sheet over it. The traces on the sheet protect parts of the board from the UV light. Then you stick the board in an etchant, and the places that got exposed to the UV light come off. The places that were protected don't.
I left out a lot of things that you have to do, but that is the main idea.