Voice of the Market (VoM) is different in that it incorporates input from the greater market. The market contains not only your customers, but also those who chose not to buy your solution Ð those who bought someone elses product and those who just didn’t make a decision.
VoC is a subset of VoM because your customers are included as a part of the overall market. It’s important to think about VoM (and just VoC), because it’s important to understand why people didn’t buy your product. Focusing only on customers (VoC) will only give you part of the picture.
Nice piece by Jennifer Doctor on why Voice of the Customer only addresses part of the market.