According to paypal docs: https://developer.paypal.com/webapps/developer/docs/classic/adaptive-payments/gs_AdaptivePayments/

The payment which is split among 2-6 receivers is known as a parallel payment. Technically, we can say that the multi payment made in single pay request are know as parallel payment. These payments are very useful in various cases where buyer intend to make single payment for end number of sellers. Examples include the following scenarios:

• a single payment for multiple items from different merchants, such as a combination of items in your inventory and items that partners drop ship for you.
• purchases of items related to an event, such as a trip that requires airfare, car rental, and a hotel booking.

On the other hand, the payment which is indirectly split among multiple receivers is known as a chained payment. This is an extended typical payment from a sender to receiver, where the receiver is also known as a primary receiver. A primary receiver, then passes a part of payment to the secondary receivers