CT scan 64-slice angiogram as well as a cath angiogram is by definition an angiogram as both involve a dye injection, but there is more intense radiation exposure with CT angiogram. It is fast becoming the radiological test of choice to look at disease of blood vessels. The next generation of a ct scan will reduce the individual's radiation exposure.
The ct angiogram involves an assessment of the body of the vessels as well as the lumen. The cath angiogram exams the lumen for hard plaque and any blockage, but the ct angiogram also exams for soft plaque within the body of the vessel. Soft plaque presents a higher risk for a heart attack as it may rupture the inner lining and form a clot.
there is the famous 64-slice CT scan, which may turn out to be better than a angiogram but isn't accepted as such just yet