The SNES version has a blue and pink outfit for the two healers, instead of the correct white one. All other instances of the outfit, including in a illustration in the intro of the same version, have the correct outfit. It is unknown why.
The GBA version has these major differences -
PSX-style status screens
The Cooking sub-quest
All the characters have got the correct look.
Cless can jump to attack, instead of needing to 'aim' at flying enemies.
A much more relaxed encounter rate. (The SNES version had a encounter every few seconds at times.)
Slightly altered enemy statistics and player attack power, to make up for the lower encounter rate.
Most of the cast was rerecorded.
The PSX version has these extra differences -
New intro and credits sequences, taking advantage of the better graphics engine.
Some effects are rendered using 3-D.
The map is in 3-D and includes the Tales 'Press SELECT for a conversation' button.
Some music has been rearranged.
Some missions have been altered.
Some locations have been remapped for ease of use.
Sprite graphics are larger and more detailed during battle.