IGRP is a Cisco-proprietary routing protocol, and does not support multiple vendor environments.

EIGRP is a classless routing protocol, and thus supports variable length subnet masks (VLSM).

EIGRP routers build a neighbor table in memory, and use a multicast-based neighbor discovery mechanism.

EIGRP routers send partial updates when there are network events.

The following are features offered by EIGRP:
* Fast convergence
* Partial updates
* Neighbor discovery mechanism
* VLSM
* Route summarization
* Scalability