‘Each’ and ‘every’ are determiners, words that are ‘used with singular nouns to indicate quantity’. There are differences between the two that are important to grasp for usage, though.
- ‘Each’ is used when there are two objects; here ‘every’ is not used. For example,
- - He wore multiple bracelets on each hand (note: singular noun).
- - There were two of them. They each carried backpacks, and eachbackpack (note: singular noun) contained invaluable souvenirs.
In case there are more than two objects, either of the two may be used.
- - He wanted each/every item on the catalogue.
- - There is a bathroom in each/every room.
- ‘Each’ can be used as a pronoun, but ‘every’ cannot. Note the difference between the following sentences:
- - The students were waiting for the question sheets to be handed out. Each was in a state of great nervousness.
- - The students were waiting for the question sheets to be handed out. Every student/one of them was in a state of great nervousness.
Clearly, ‘each’ replaces the noun ‘student’. ‘Every’ does not; it requires to be followed by the noun, or by ‘one of them’.
- With adverbs (practically, nearly, almost, etc), only ‘every’ is used. In the following sentences, ‘every’ cannot be replaced by ‘each’:
- - She knew practically every detail of his daily routine.
- - Nearly every fruit on the cart was spoilt.
- ‘Every’ is used to refer to repeated, regular events, as in the following cases:
- - We meet every so often
- - I get a health check-up done every six months.
- - I had to take a water break after every other set.
In the above examples and any similar instances, ‘each’ cannot be used.
Take from: http://www.englishleap.com/common-mistakes/each-every
