Below you will see a quick comparison between Cedar wood and Pressure Treated Pine wood. 
Cost
Cedar is not always readily available and thus the price may be higher at certain times in the year. Cedar will often cost 1.5 to 2 times as much as pressure treated wood. Pressure treated pine wood is readily available and often not expensive.
Look
Cedar gives your fence project a much more natural look than pressure treated pine. Natural Cedar is a soft wood that comes with very little imperfections and there is no warping, cracking, or shrinking, and hold up very well to the elements. Pressure treated lumber often is speckled with knots and other imperfections and sometimes can begin to twist and warp soon after leaving the wood mill.
Maintenance/Upkeep
Cedar unlike pressure treated lumber is not chemically treated to fight off wear and tear from the weather. Cedar has many natural properties that help it fight off the weather elements, however it is highly recommended to seal the Cedar with a clear seal to retain the wonderful natural deep red color.