Nova Corps - Originally, the Nova Corps was Xandar's space militia and exploration division. It consisted of 500 soldiers ranging in rank from Corpsman up to Centurion and its leader, Centurion Nova Prime
Nova Force - The Nova Force is the source of power for Nova and the entire Nova Corps. Generated by the Living Computers, the Nova Force gives the recipient the abilities of super-strength, super-speed flight, invulnerability and a link to the Living Computers itself. The Nova Force can be used to generate a Gravimetric Pulse (a high energy burst of force) and can absorb energy from an opponent's weapon. With proper control, the Nova Force can also open a Star-Gate, generate an Electromagnetic Static Burst (which halts an opponent's motion relative to the rotation of the Earth thus hurling him a great distance), and cause a seismic ripple by being tightly directed into the ground
The highest ranking officer and overall leader of the Nova Corps is the Centurion Nova Prime. The higher your rank the more Nova Force is given to you through the Worldmind.
According to Geoff Boucher over at Entertainment Weekly, not only will the Nova Corps be in the film, it is possible that Marvel superhero Nova may show up as well.