What is the difference between ipod skins and ipod cases?

because i just wanna get a hello kitty cover for a cheap price but i heard like one is a sticker and another is like hard? im confused...=/What is the difference between ipod skins and ipod cases?
ipod skins are little rubbery things and cases are hard protective shield for it as i might sayWhat is the difference between ipod skins and ipod cases?
A Skin is Normally made of Neoprene(Like a Wet-Suit) and fit tightly around the Unit.


A Case is More robust and is made for everyday Use!


I use a Contour Cases for my iPods, and they Look very Minimal ,but protect and allow access to all ports!

eye look