I don't know about you, but I've always wondered what the difference is between all the different olive oils. I thought I'd do some research.
Extra Virgin Olive Oil is the purest type of olive oil you can find. When the olive is pressed, oil comes out and if the olive was of the highest quality it will be pure olive oil, making extra virgin olive oil.
However, if the olives aren't good quality, then the oil that comes out of the pressed olive has to be refined further, which results in a lighter color. This starts the progression through the different types of olive oils and why the variation in the colors.
So in synopsis.....
"Extra" means more money but a better quality. Always use this type for dressings.
"Light" means less money so you can save a little bit of money by using this type of olive oil to cook with.