Fare difference between DL and AF
 

I am trying to book a flight from BNA-MAD then CDG- BNA in July

I looked at both DL and AF website. There is a $300 difference between the sites but they use the same exact planes (flights). I have more SkyMiles as I am based here in the US. What will be my best option- i still want to earn SkyMiles but i don't want to pay the extra $300 for the same flight

Thanks

Just give your Skymiles number as your FF number at booking and you will earn Skymiles, regardless of which website you use.

If you care about status, DL operated flights will earn more MQMs if booked as DL-coded flights during 2021 due to Status Accelerator promotion. MQD and Mileage earnings may be more or less with Accelerator promo as AF booked flights with AF flight numbers will earn MQD/miles based on mileage-flown rather than fare paid. If you don't have DL status and don't care about earning it, just go with the AF booking and enter your Delta Skymiles number on AF website as noted above.