The Japanese PSX version has some differences.
(1) Mainly, it has two exclusive familiars: A "sprite familiar," which resembles the "faerie familiar," that can use a music card to sing a song; this one is located in Olrox's Quarters. The other is "Tengu Goblin," a funny-voiced familiar with a sizable nose. The voice is apparently that of a famous Japanese actor, and it was put in as a joke. This one can be found in the Colosseum.
(2) Also, the Japanese version features more in the way of blood and gore, like the Medusa Heads that squirt blood when they die.
(3) And then there are the usual name deviations; most notably: Thornweeds are known as "Unes," Stone Roses are "Man-Eating Flowers," Cave Trolls are "Chupacabras," Hellfire Beasts are "Amdusias," Diplocephaluses are "Amphisbaenas," Karasumans are "Malphuses," Skeleton Dancers are "Skeleton Jumpers," Cloaked Knights are "Flying Armor" and Lossoths are "Biphrons." Also, strangely, Malachi and Ctulhus names are reversed. To more effectively learn about these changes, check Aria of Sorrow's page--since that game didn't receive much localization as far as name-changes, many enemies from this game show up there under their true names.
(4) Finally, in general, it's any easier game--about Harmony-level.