When a plant tag tells you Full Sun, take into consideration the location. With our southern summers some areas can get darn hot! When does it get full sun? In the morning or afternoon? The general rule for Full Sun is 6 to 8 hrs of direct sun.
Part Sun / Part Shade
I have always found both of these light requirements to be interchangeable depending on the plant. Some plants will prefer morning to early afternoon sun, while others won't mind the late afternoon sun. Part Sun / Part Shade is as little as 3 hrs up to 6hrs of sun.
Dappled sun is the sunshine that makes its way through the branches of the overhanging canopy.
Full shade is less than 3 hrs of direct morning or very late afternoon sun. These plants need to be protected from our hot summer sun.