Okay, Famitsu's website confirms the following info. I'm not going to translate the entire trailer descriptions since other sites will do it. But here's the info breakdown:
KH 358/2 Days:
- Begins with the ending of KH Re:CoM, and mentions "the opposite side of time, while Sora was sleeping".
- The entire game is centered around Roxas, and his time while Sora is asleep, as expected.
- XIII Org game total. 4 player multiplay.
- Ends with "In another 151 days, I will disappear from this world..."
KH Birth by Sleep:
- Begins with the the KH ending going backwards to the Opening. "The distant past", "Destiny is born from the sleeping secret".
- Takes place in Hollow Bastion.
- Features the characters from the KH2FM+ secret ending, including the old man.