Citi Diamond Preferred Rewards Amex & MC? What's the difference?

[TheCreditKid]

I compared the Diamond preferred rewards AMEX & MasterCard on Citi's website but cannot find anything different between them. Are they basically the same card with just different names? Why would citi have two of the same card but one is from AMEX & the other from MasterCard? Because the service and rewards are basically identical...

[MrShush]

AFAIK, they are the same in terms of rewards (Thank You rewards), but you get some of the cache of AMEX and access to concert ticket presales, AMEX Selects travel discounts, AMEX travel ATMs, and AMEX travel offices.