What are the differences between vascular dementia and alzheimer's disease?

Not many: Clinically, alzheimer's tends to be a smooth decline over time, while vascular dementia declines in steps, as small regions of the brain lose function. Neuropsychological testing may lend evidence for, but not prove, one cause or the other. A definitive diagnosis can only be made by brain biopsy (which is rarely done), or at autopsy.

The course of illnes: Is one of the major differences. Vascular dementia shows a stepwise loss of memory and function, while alzheimer's course is slowly progressive.