The USB port on the Odroid HC2 is 2.0, but the SATA interface is connected to a USB3 but, as is the Gigabit Ethernet.

Furthermore, SATA and Ethernet are connected to individual USB3 busses, as opposed to earlier RPi designs where everything shared the same USB2 bus.

I haven't checked the RPi 4 specs yet, but i can imagine it's still the same layout, just a faster bus, which can be "just fine" - it should be plenty fast to saturate a Gigabit ethernet as well as the SSD/HDD IO required to do that.