Watts indicate how much power the bulb uses:
It used to be as easy as finding the correct bulb by just looking at the wattage but now with lower watt LED and CFL light bulbs that consume 80% less power this number isn't as helpful
You can see here that LED light have a much longer life than other bulbs and also use much less energy (about 80% less)
Lastly you want to check the color temperature chart:
The color chart is measured on the Kelvin scale. The higher the number the more "cool" the bulb is and the lower the number the "warmer" the bulb is.
Cooler is considered a brighter white light where as warmer is a more yellow/orange color. This chart will help you decide where in your house you might use the different bulbs and what "mood" they are associated with
source:- http://imgur.com/gallery/d2ztt
