None. You need to look at interface the NIC is connected to the CPU. Sometimes MAC is built into SOC and board just needs PHY, that can be easily line-speed.
Sometimes it's via PCIe (usually pcie to usb+ethernet) chip, then it's usually also line speed. Well, at least till you start using USB3 heavily
Sometimes you just get USB3 NIC or worse, USB2.
Wireless can also be funky, I've noticed using BT and Wifi at same time absolutely destroys wifi speeds on my rPi4
Hell, in theory even builtin MAC doesn't guarantee line speed, all depends on internal architecture.
Sometimes it's via PCIe (usually pcie to usb+ethernet) chip, then it's usually also line speed. Well, at least till you start using USB3 heavily
Sometimes you just get USB3 NIC or worse, USB2.
Wireless can also be funky, I've noticed using BT and Wifi at same time absolutely destroys wifi speeds on my rPi4
Hell, in theory even builtin MAC doesn't guarantee line speed, all depends on internal architecture.