When you enter a street address along with your search term, Yahoo! Local calculates the distance from that particular street address. When you enter your search term along with a city or a city and state, Yahoo! Local calculates the distance from the city center to the business you're looking for. As with all areas of Yahoo! Local, the more specific you are with your address, the more precise your calculation will be and the more exact your results will be. For instance, "54th Street, New York, NY and kosher delis" will get you better results than "New York, NY delis."