OpenWire is the native protocol that Apache ActiveMQ uses. It is designed for performance and size on the wire - sacrificing some ease of implementation with higher performance and reduced network bandwidth as a priority. OpenWire was first released in Apache ActiveMQ 4.0.
Stomp is a simpler text based protocol which is designed to be very simple to implement in a few hours in any language or platform (e.g. you can use a telnet client to communicate via Stomp). A Stomp client is not going to be as efficient as an client that uses