ASUS P3V133:
3ISA, 4PCI, 1 AGP, 3 DIMM
VIA 693 Apollo Pro 133 chipset.
AGP2X, low performance.
BIOS controlled Asynchronous SDRAM/FSB setting.
PCB based on the older P2B (rev 1.13).
Jumper control...16 available FSBs.
No Vcore adjustment.
ASUS P3V4X:
1ISA, 6PCI, 1AGP, 4DIMM
VIA 694X Apollo Pro 133A chipset.
AGP4X, very good performance
PCB based on the P3B-F.
BIOS controlled Asynchronous SDRAM/FSB setting.
Dipswitch and Jumperfree (BIOS) control....32 or 16 FSBs available.
Full Vcore adjustment.
Those are most of the main differences.