It is a compilation that contains both Psyvariar -Medium Unit- and -Psyvariar Revision-.
New features include:
Option to use a separate button to roll
SECRET LAB jukebox
Ability to display hit boxes
Two special editions were also available in Japan. The Special Sound Box included an audio CD of the game's soundtrack, and the Special Capture Box included a gameplay DVD of both games being fully completed by expert players. The PlayStation 2 version of the individual games were later released separately as budget range titles.
European version retained all the features of the Japanese release and includes a 60 Hz mode.
Source: Wikipedia, "[en.wikipedia.org/wiki/Psyvariar%23Psyvariar_-Complete_Edition- Psyvariar]", available under the CC-BY-SA License.