The difference between the Lancaster Turnpike and the National Road that stands out in the context provided is:
B. only one bound different regions together.
While both the Lancaster Turnpike and the National Road contributed to improved transportation and promoted westward expansion, the National Road specifically served to connect the eastern United States with the western frontier, effectively binding different regions together. The Lancaster Turnpike primarily served the region of Pennsylvania, facilitating travel and trade within that area rather than connecting distinct regions.