"A business absolutely devoted to service will have only one worry about profits. They will be embarrassingly large." - Henry Ford
Selling a product is a far different prospect than selling a service. Generally, buyers will know the fundamentals of what your product is, how it works and maybe even why they need it.
Services on the other hand can be a far more nebulous value proposition to try and define for a prospective customer. You can't hold it in your hand, and understanding how to differentiate the value of one service over another can ultimately come down to preconceptions and hinge upon 3rd party references.
To win in today's competitive marketplace, service companies must begin to think differently about how they go to market, position their service offering and solve for their customers' challenges.