Due to the grinding and compression of the hop pellets they tend to be a more stable product and less subject to oxidizing than whole hops. This is a big reason pellet hops are often used in commercial brewing and are more readily available on a homebrew scale. Whole hops are often used in dry hopping beer as they are easier to remove from the beer and may give a slightly fresher aroma than pellet hops, which lose some of the flower's essential oils during the pelletization process. Whole Leaf Hops do take up more space in the fermenter. The difference in hop flavor is slight, if any, and pellet hops also work quite well in dry hopping situations.
Looking for dried or leaf hops for sale? Northern Brewer has you covered.