Difference between "each" and "every"

[Pstein]

What is the difference between "each" and "every" ?

Is there a negation of both?

none for each

and

??? for every

Peter

[Sua]

Look at these:
a) There are four flats in our building. Each flat has a balcony. (we are emphasizing the individual flats)
b) One good thing about living in Athens is that every flat has a balcony (talking about flats in general)

negative of both is neither I guess
and none is used for each and every.