A "cardiac surgeon" or more commonly known as a Cardiothoracic surgeon, typically completes 5+ years of a General Surgery residency and 2+ years of a CT surgery fellowship. There is some talk of a 4+2 track for CT surgery ("fast-tracking" medical students straight into the field with 4 years gen surg followed by 2 years CT surg) - however, I've yet to see any programs actually start to matriculate residents into such a program.
Really no difference between Cardiac and Cardiovascular except that Cardiovascular surgeons probably emphasize doing more peripheral vascular cases (which typically falls to the Vascular Surgeon). CT fellowships have more or less thoracic experience depending on the program.