I think it can be the same with web shops. I mean, why would I buy from YOU specifically? We're lucky in that we have the software product line and I've got a fairly good reputation now from conference presentations, published articles and the like. We also have a unique process for building web apps quicker and more cost effectively and are continuing to invest in our systems to improve the quality and productivity of our solutions.
What are your thoughts? What differentiates the business you work for? Vertical industry experience? The quality of your devs (what about them?)? Processes? Systems? Testimonials?
I'd be interested in hearing how you differentiate yourself - whether as a company or as a freelancer and what you find "sells" and what doesn't!