Difference between arbitration queue and request fifo

Is arbitration queue and request fifo in context to sequencer are same or they are 2 different subcomponent within sequencer ? If they are different then what is the difference ?

Each sequencer has a request fifo. Calling get_next_item/get remoes the seq_item from the request fifo.
An arbitration queue is used in virtual sequencer. They do not generate itself seq_items but they are orchestrating the execution of agent sequencers depending on the arbitration algorithm.