Not sure if sarcastic or not because it's pretty obvious, but I will elaborate (assume Platinum or Diamond when I refer to Medallion):
- Basic economy passengers lose the ability to do a same day change at a cost. Medallions lose the ability to do a same day change and lose the ability to receive a $75 discount.
- Basic economy passengers lose the ability to pay for a Preferred seat at cost. Medallions lose the ability to select a Preferred seat and lose the ability to select one for free.
- Basic economy passengers lose the ability to pay for a C+ seat at cost. Medallions lose both the ability to pay up for a C+ and also lose the ability to select available seats for free.
- Basic economy passengers lose the ability to pay up for a F seat at cost. Medallions lose both the ability to pay up for a F seat and to upgrade into one for free.
- Basic economy passengers and Medallions both lose the ability to do changes for a fee. This is an equal loss.
- Basic economy passengers and Medallions both lose the ability to select non-preferred seats. This is an equal loss.
Medallions have additional restrictions. You have to decompose the option to, e.g., pay for a seat versus the option to pay for the seat and effectively receive a discount for it (i.e., it being free in the case of an upgrade). These are two separate set of restrictions. Medallions face greater restrictions. I am not sure why I have to spell this out.