What is Nano Zinc Oxide?
Nano zinc oxide is a real material used in sunscreens and looks like this.  It is just little crystals of zinc oxide which are about 30 nm across.

Chelate refers to something which is produced by a chemical process of chelation.  Chelation means that a metal atom has more than one chemical bond to surrounding organics.  (That is kind of a bad definition, but I'm trying to keep the lingo simple.)  Chelation can be used to produce zinc oxide, but I don't think this is the process used for manufacturing most industrial zinc oxide.