Mass Effect 2
With elaborate secrecy, Cerberus labored for years to build a new, superior Normandy. The vehicle's many alterations produced a craft nearly double the original size, requiring an even larger Tantalus drive core to compensate.
The new Normandy features greater space in living quarters, research laboratory, observation deck, and cargo bay. Its shuttle can make landings the Normandy cannot attempt. In addition to tightbeam communications, Normandy's Quantum Entanglement Communicator (QEC) provides instantaneous contact with the Illusive Man. The Enhanced Defense Intelligence AI coordinates many of the ship's combat functions, assisting and even supplanting human piloting.
Potential upgrades are numerous; the airframe could support additional armor and an axial mass accelerator, the thrusters could support recent advances in fuel technology beyond H2/O2 chemical rockets, and the hull can mount double the standard number of kinetic barrier projectors, leaving space for stronger shields, easily sustainable via the new eezo drive core.
Mass Effect 3
Cerberus built the Normandy SR-2 as a second-generation version of the Alliance frigate SSV Normandy after the Collectors destroyed the original. The SR-2's many alterations produced a craft nearly double the original size, requiring an even larger Tantalus drive core to compensate. Its state-of-the-art Kodiak shuttle can make landings the original Normandy could not. The Enhanced Defense Intelligence, an AI known colloquially as EDI, coordinates many of the ship's combat functions, assisting and even supplanting human piloting.
The Alliance has recently appropriated and refurbished the SR-2. In addition to tightbeam communicators, the Quantum Entanglement Communicator provides instantaneous contact with Alliance Command.