What is ENI (Elastic Network Interface) in AWS? (72/285 technotes for 2015)

Elastic Network Interface is a Virtual Network Interface that you can attach to an instance in VPC.

NIC - A network interface is the point of interconnection between a computer and a private or public network. A network interface is generally anetwork interface card (NIC), but does not have to have a physical form. Instead, the network interface can be implemented in software.

For eg: Loop back address or 127.0.0.1 is not a physical device - but a software simulating a network device

References:

http://bit.ly/1bEtFc0