The difference is wealth. If you own a large country house, several horses to bugger at night, and a velvet smoking jacket to throw off and dance naked around the mansion grounds, you are "eccentric".
If you live on a council estate and do those things, you are insane/mad.
Voted : The difference is.... I'm considered eccentric, and I believe in the afterlife, UFOs and real justice in the world. Crazy can't fathom those concepts, IMO.