Refer to the Following Passage to Answer the Questions Below

Refer to the following passage to answer the questions below.
Haley and Lauren, who recently graduated with MBAs, are opening a new shoe boutique called The Pampered Soul in Hattiesburg, Mississippi, which is classified as a Metropolitan Statistical Area (MSA)with more than 100,000 people. It's also home of The University of Southern Mississippi. Haley and Lauren will offer national brands of shoes that are not available in the department stores in the mall, and their primary target market will be women ages 18 to 35. They've rented a location on the main street in front of the USM campus. The owners realize that most of their business will come from a five-mile radius and want to limit their advertising to those potential customers. They have a modest budget for advertising, so they want to get as much out of it as they can.
-Haley and Lauren are trying to figure out the reach of their newspaper advertising. They saw that the Hattiesburg American had very different numbers for readership and circulation. Why is that?