How do diltiazem, verapamil and nifedipine differ? do they all do the same thing and work the same way as it relates to vasodilation and vasospasm?

Same but different: All 3 are calcium channel blockers but are chemically different with different side effects, doses, and durations. Nifedipine is in the dihydropyridine class and the other two are not. Nifedipine doesn't affect conduction but the other 2 do. For more details, see: http://www.differencebetween.net/science/health/drugs-health/differences-between-dihydropyridine-and-nondihydropyridine/