Dead or Alive 5 Ultimate is an updated version of Dead or Alive 5. Ultimate includes new modes and some features from Dead or Alive 5 Plus, as well as several new stages and fighters, and all-new features such as two-on-two online multiplayer tag team battles.
A free digital version, titled Dead or Alive 5 Ultimate: Core Fighters, which features four playable characters and the online mode, with additional characters and story mode content available as purchasable downloadable content.
Dead or Alive 5 Last Round is the third updated version of 2012's Dead or Alive 5. Last Round includes all the features and content from Dead or Alive 5 Ultimate with additional new costumes and customizable hairstyles, as well as two new characters and two new stages. The original Dead or Alive boss Raidou returns as a cyborg, along with a new female character named Honoka. The PlayStation 4 and Xbox One versions will feature upgraded graphics, running at 1080p resolution and 60 frames per second. The game uses a new Soft Engine, designed to better depict "softness" of characters' bodies.
Source: Wikipedia, "Dead or Alive 5 Ultimate", available under the CC-BY-SA License.