|No difference at all on most boards. As OtheHill said, some really old motherboards run the front ports at USB 1.1, but any board made after 2002 would be all 2.0.|
Front panel audio is a different story. You'll usually get much better sound out of the back audio ports.
mATX Beast | LGA2011 i7-3930K @ 4.2GHz | 16GB quad-channel DDR-1866 | GTX 670
240GB SSD+2TB HDD | Asus Rampage IV Gene | Seasonic X560 | Silverstone TJ08-E