Find your point of difference

When I ask clients what sets them apart from their competitors I generally receive one of the following responses:
Quality
Service
Cheapest
Fastest

Well that may be true, most of them stumble with the following question – How would a potential client, customer know that you are ….. (insert response from previous question).
Unless you have won an award for service, have consistent 5 star ratings then If you are unable to demonstrate that point of difference then its game over.