There are two different delivery types for making deliveries with Amazon Flex: Amazon standard and Amazon Now.
You will need to select your delivery type in the Amazon Flex app during onboarding. Once selected, you will not be able to switch, and will only see offers for that delivery type in the Amazon Flex app when you have completed onboarding.
With both Amazon standard and Amazon Now, deliveries are organized into blocks. The delivery types vary by block length, the vehicle you can use to deliver, and the number of trips that will be made in one block. Delivery routes are designed so that they can be safely completed within the scheduled block time, taking into account factors such as size and weight of packages, driving distances, weather and road conditions, and more.