In boiling, most or all of the molecules in the liquid have enough energy to leave the liquid and become gas. The whole liquid will be near or at the boiling temperature.
In evaporation, the liquid will normally be much cooler than boiling temperature. However, because of the way that molecules pass energy from one to another (Brownian Motion), not all the molecules will have the SAME energy. In fact, some will have lots more than others. These very energetic molecules, if they are near to the edge of the liquid, may have enough energy to escape from the liquid and become gas. The process of molecules leaving will gradually mean that the liquid all evaporates away.
Hope that helps

What's the question?