Double reed calls are easier to learn on, and easier for beginners because they are a little more forgiving to mistakes made by the hunter. Double reeds are raspier than singles reeds as well.
Single reeds are a little more difficult...not much though. Single reeds aren't as raspy so you have to put a little more voice into them. They are generally louder than double reeds too. The thing that makes single reeds a little more difficult is the reed sticks more, and they are more sensitive to back pressure, so you can sound like a duck having a stroke really easy if you blow it wrong.
