What's the difference between dementia and alzheimer's disease?

Alz =1 type dementia: The term 'dementia' describes a set of symptoms which include loss of memory, mood changes, and problems with communication and reasoning. These symptoms may occur when the brain is damaged by certain diseases. Alzheimer’s is the most common (but not the only) cause of dementia.

Dementia: Can be caused by a númer of things, one of which is alzheimer's disease. Other causes include alcohol, stroke, head injuries, Parkinson's disease and others.