What is the Difference Between Similar But Different Things, Terms, and Objects

What is the Difference between Parkinson’s, Senility, Alzheimer’s and Dementia

Parkinson's, Senility, Alzheimer's and Dementia are brain related diseases but very confusing due to many similarities in symptoms. People usually get confused about the difference between these four brain related diseases. Obviously, for proper treatment of any disease, it is very necessary to diagnose the diseases exactly.