Dead or Alive for the Saturn and PS1 are actually two different games, the PS1 version is an update
to the original Dead or Alive on Saturn and the arcades.
The Saturn game uses a minimum of two layers of 2D backgrounds, usually with animated background elements
like waterfalls, and texture mapped characters with no lighting or shadows. The PS1 game uses one flat
2D background, with no animation except in Tina's level, and non-texture mapped gouraud shaded,
or lightly texture mapped with no textures in some areas, characters, with shadows.
The PS1 version also has different floor textures for the danger zones than
the Saturn game has, and is supposed to have more costumes to choose from. The
Saturn version has more detailed ring textures, and no warping, while the PS1
game has an issue with the textures warping, or poping out of place, as many
PS1 games have.
The Saturn game shows your
character in the outfit you've selected in the character select screen, while the PS1 game does not.
The difference between flat shaded characters with lighting, and detailed texture mapped characters
without lighting is dramatic, and creates a unique look for each game.