There is a difference in serial interface of NRF52840-QIAA-R7 and NRF52840-QIAA-R but its datasheet is same in Digi-Key

[Vikas Bhatt]

NRF52840-QIAA-R7:-    Sensitivity:   -103dBm
                                       Serial Interfaces:     ADC, I²S, PDM, PWM, SPI, TWI, UART, USB

NRF52840-QIAA-R:-     Sensitivity:    -96dBm
                                      Serial Interfaces:-     I²C, I²S, SPI, UART, USB

There is a difference in serial interfaces of nRF52840.

                                     

[Daniel Chisholm]

Just an error by Digikey.  The distributors usually get most things correct but they do make mistakes at times and I think this is one of them.  Notice they also listed different Rx sensitivities.... -96 would be for standard 1Mbps and -103 would be for 125 Kbps

They are the same device, one is on a 7" reel the other is a 13" reel.  So it is correct that they both have the same datasheet.