Originally Posted by Beckles

I would expect you will both receive miles, but if you're crediting to Delta there is a difference in miles earned according to this page.

ORD-MEX-EZE is 6,270 miles each way.

The D fare will earn 18,810 RDM and MQM (plus any Medallion bonus) and $3,762 MQD while the J fare will earn 25,080 RDM and MQM (plus any Medallion bonus) and $5,016 MQD, enough for Silver Medallion in one trip.

For my situation the refundability is a big plus anyway and the miles are gravy, enough to give my wife Silver and all but assure me of earning Platinum again this year with a nice rollover ... if we take the trip.