Two postal delivery workers have different routes. They both travel from the same post office to neighborhood to delivery now and then back to the post office, which must be true about the two postal delivery workers.

1. They both start and end their delivery routes at the same post office.

2. They deliver mail in different neighborhoods.
3. They travel on different routes while making their deliveries.
4. They both return to the post office after completing their deliveries.
5. They have different schedules for when they deliver the mail.
6. They may have different methods of organizing and sorting the mail.
7. They may interact with different customers or recipients during their deliveries.
8. They may cover different distances while making their deliveries.
9. They may have different types of mail to deliver based on the neighborhoods they serve.
10. They may use different means of transportation for their deliveries.

1. Both postal delivery workers start their routes from the same post office.

2. They both travel to different neighborhoods to make their deliveries.
3. After completing their deliveries, both workers return to the post office.
4. The workers may have different routes or delivery schedules within the neighborhoods.
5. The workers may have different work hours or shifts.
6. It is possible that each worker has a specific set of neighborhoods they are responsible for.
7. The workers may use different modes of transportation to carry out their deliveries.

To determine what must be true about the two postal delivery workers, we need to analyze the information provided.

1. Both workers have different routes: This means that the paths they take to deliver mail are not the same.

2. They both travel from the same post office to neighborhoods: Both workers start their routes at the same post office and then proceed to deliver mail in various neighborhoods.

3. They deliver now and then back to the post office: After completing their deliveries in the neighborhoods, both workers return to the post office.

Given this information, the following statements must be true about the two postal delivery workers:

1. They start their routes from the same post office.

2. They deliver mail in different neighborhoods.

3. They both return to the post office after completing their deliveries.

It is important to note that there could be additional information or nuances that are not provided in the question, but based solely on the given information, these statements must be true.