After Omega introduced their Co-Axial escapement technology in 1999, they began applying it to other movements. Cal. 3303 was a popular chronograph movement for the company at the time, so it was natural that they fit it with this technology.
Cal. 3113 is a later development of Cal. 3313, featuring 3-level Co-Axial escapement and a free-sprung balance.
Cal. 3201 is a hand winding variant of Cal. 3313.
Cal. 3202 features the free-sprung balance and small seconds
Cal. 3203 features the free-sprung balance and small seconds
Cal. 3205 lacks a date window
Cal. 3603 adds a GMT 24 hour hand.