Sport Bowling or Challenge leagues use oil patterns to provide the same type of lane conditions used on the professional level and in international competitions. A few things to note about Sport patterns:

Sport or Challenge patterns typically have an oil ratio of 4:1
The lower the oil ratio, the more difficult the pattern
Patterns have different shapes
The “house” patterns used in many leagues typically have an oil ratio of 6:1 or higher, and average around 40 feet in length

To better understand the difference in the patterns used in a Sport or Challenge league versus a typical “house” league, check out the video below.