Answer
When the radios are Direct addressed to each other, meaning the MAC Address of the paired receiver radio is configured in the Destination Field, they are in what is known as Addressed Acknowledge Mode. When in this mode, the RF packet is sent out to the receiver designated by its Destination Address. Max Transmit Retries is used to increase the odds of successful delivery to the intended receiver. Transparent to the OEM (Other Equipment Manufacturer) Host - your device, the transmitter will send the RF packet to the intended receiver. If the receiver receives the packet free of errors, it will send the transmitter an acknowledgement. If the transmitter does not receive this acknowledge, it will assume the packet was never received and retry the packet. This will continue until the packet is successfully received or the transmitter exhausts all of its retries. The received packet will only be sent to the OEM Host if and when it is received free of errors.
When the radio is configured in Broadcast mode, by enabling Broadcast in the Radio Features section, the radio is in Broadcast Acknowledge Mode. While in this mode, the RF packet is broadcast out to all eligible receivers on the network. Broadcast Attempts is used to increase the odds of successful delivery to the intended receivers. Transparent to the OEM Host, the transmitter will send the RF packet to the receivers. If a receiver detects a packet error, it will throw out the packet. This will continue until the transmitter exhausts all of its attempts. Once the receiver successfully receives the packet it will send the packet to the OEM Host. It will throw out any duplicates caused by further Broadcast Attempts. The received packet will only be sent to the OEM Host if it is received free of errors.