The 03 has other differences from the 01, like no waveshaping and no floppy drive.The 03 is NOT SysEx compatible with the 01.
Prog/Combi Cards
The 03R/W has some 01 Multi-Sounds and some unique to the 03. This means that any Prog/Combi cards made for the 03 will likely not sound right in an 01 (even if they use the same PCM card). In fact, I've been told the Prog/Combi card for the 03 will not work in the 01 - you will get a "No data/card" message. The 03 uses "UPC" cards but the 01 uses "XPC" cards.
PCM Cards
The 03 uses the same PCM cards as the 01. There are no separate PCM cards for the 03.
http://net.indra.com/~cliffcan/01faq.htm