Question about Lenovo 4x90q84427

The adapter uses the on-board Ethernet interface and thus also the MAC address of the PC. The UBS-C adapters always have their own MAC address. Unfortunately, the plug is so wide that the USB-C port directly next to it can no longer be used when the adapter is plugged in.

Your notebook already has an Ethernet adapter on board. Unfortunately, the notebook is so flat that the connection for the cable did not fit into the housing.
The advantages of the onboard (pci express) over a USB-C variant are lower latency and CPU load and higher maximum throughput.

that the USB space remains free for other