To add on the above.

The FLA movies are lower resolution on PSX but they have more colours, so there are no colour banding. PC are higher resolution with reduced colours as the palette is shared across different frames.

Twinsen model is also different, it's head has been upgraded although hardily noticeable because of the lower resolution of the PSX.

There's a 3D Adeline Logo with Intro Image with different copyright notice, and with a loading screen. Font is different and seems it was replace to use less screen space due to the cropped version of PSX.

Holomap island transitions are different, they don't show the transport method in the bottom left corner.
Overlay is showed on somoe items only like the Gas (now at the bottom right corner)

Inventory Text and Voice Over has been changed to remove the PC specific instructions like Keyboard keys, and only text was updated for the PS1 Controller.

Some software rendering methods have been removed, like the old schooll copper rendering that we can seee in the Fishing Boat or the Garbage Truck head lights.

PSX version fixes an importang lock bug that can happen in the Museum, as you can get the Key without having the red card, causing you to get locked and having to restart from a previous save. They fix it by blocking the museum sewers access with some barrels.

PSX Japanese version was more a direct port from PC outsourced to include the translations, and has some performance issues. The EU version was made by the Adeline studio and is a better port.