Are there any differences when it comes to playing PS2 Content in the PSX? What about unsupported features?

The PSX (not to be confused with the PS1) was a Japanese exclusive DVR that it came with a PlayStation 2 inside of it, kinda like the Nintendo Gamecube inside of the Panasonic Q DVD, also exclusive to the Japanese market.

When it comes to using the PSX as a PS2:

• Are there any differences in the use of the PS2 features? (game startup, Memory Card data management, etc)
• Are there some PS2 features that are unsupported on the PSX? (the Wikipedia article says that HDD games are sported like FFXI, but nothing about accessories and other software)