This article explains how to switch between various types of ZIP code layer: U.S. Census, USPS (U.S. Postal Service), and USPS with fillers ZIP codes.
Map Business Online provides access to both U.S. Census ZIP Code Tabulation Areas (ZCTA) and U.S. Postal Service ZIP codes. ZCTA boundaries change quite rarely (about once in 10 years) but U.S. Census updates demographic data annually. On the other hand ZIP code boundaries change every quarter and demographic data supplied by U.S. Census is extrapolated from ZCTA to ZIP code boundaries. Depending on your business needs and internal processes you may choose to use ZCTA or ZIP code boundaries in your territory design project.
There are no ZIP code boundaries defined for unpopulated areas of United States. That’s why if you use USPS ZIP code layer you will see some empty areas on map. To cover these areas with a boundary use USPS ZIP codes with fillers option