Sorry, I was off a bit on my international flights, I fly mostly domestically. And in the above lists, I think that mersk862 means "International" instead of "Business" and "Domestic" instead of "First". Also, I had forgotten about C, I, and S, but there is definitely J (which is full fare Business on Delta Metal, whereas C is full fare Business on codeshares - at least from what I can tell, other with more international experience might know more). And D, S, and I are all discounted Business.

Also, I just realized that there is a really easy way to identify the order - When booking a flight on Delta.com, you are able to select the fare class, and they are listed in order from lowest to highest. Here is the complete list in order from highest to lowest based on that list.
F, J, C, A, D, S, I, Y, B, M, H, Q, K, L, U, T.

But since you can't actually book all of these fare classes for both domestic and international flights, here are the lists broken down.

Domestic (premium cabin is called "First"):
F, A, Y, B, M, H, Q, K, L, U, T

International (premium cabin is called "Business" - except perhaps on some codeshares):
J, C, D, S, I, Y, B, M, H, Q, K, L, U, T

Note that these are not always the order in terms of highest to lowest price. Within cabins, these are generally listed highest to lowest in price, but not when comparing between cabins. For example, Y fares (and possibly B and M fares) are usually more expensive than discounted premium cabin fares (A, D, S, I). Also note that for international travel, you won't find all 5 business fares available on the same flights. I think J and D are for Delta metal and C and I are for codeshares (not sure about S).