Pharmacies get pills from different suppliers. To try to ensure that you get your prescription in a timely manner, a pharmacy will usually go with the supplier that has product in stock at the time it is needed.
Depending on the supplier of your birth control, pills may come in a different color, shape, or markings. So even though they may look different, have a different brand name, or come in different packaging, they have been FDA-approved as a pharmaceutical equivalent to the brand product. Rest assured you are getting the same active ingredient(s), dose, and dosage that you had before.