The basic difference between a single and double reed is the tone or tones able to be produced by the call. With a double reed, you basically get one "pitch" no matter how you put air in the call. On most well made DR calls, that one pitch is definitely a duck....but it is only one duck. This is because the top reed restricts the bottom reed with respect to the distance it can move. A single reed, on the other hand, will produce a wide range of "pitches" and is limited only by the operator's proficiency in blowing one, not by an extra reed. (i.e. you can sound like many different ducks.) (Obviously we are talking about a single reed duck call that is well manufactured and a capable tool. There are many good calls on the market today.) As far as starting off with a double reed then going to a single reed...at all of my seminars, I HIGHLY discourage this practice. IT does way more harm than good. The calls operate totally different! It's like saying, go play European Football (Soccer), then when you get good at it, switch over to American rules. Just ain't the same game...My suggestion is this; If you like how the DR's sound and blow then stick with them...If you like the way a SR sounds then stick with those. SR's are harder to learn BUT, in my opinion they are worth the extra practice time.