The UD3H has two more SATA connectors, supports a slightly higher memory overclock, has a "slightly" better Realtek audio chipset, has an extra audio port, and has two more USB ports.
Looking at onboard features, it has:
And extra system fan header
A power button
A reset button
A Clear CMOS button
Voltage measurement points
A dual BIOS switch
Overall if you plan on overclocking or tweaking at all I suggest the UD3H, since features like the dual bios may come in handy. If you feel that these features would be of no benefit to you, the other board would be perfectly fine as well.