May be its a dumb question but can somebody explain the fundamental difference when you say a pcie or a Ethernet drivers. As such there are many networking cards with pcie interface.
Consider below two hardwarwe example and please help me understand how a driver developer has to differ in his approach in both cases for writing corresponding driver.

1. A typical pcie Lan card which helps the host to connect to the network


2. Some pcie card which has complete TCP/UDP stack on the device itself and need to pump only payload from the incoming packets.

Please ask questions if not clear. Thanks in advance