Each of them has a dictionary.

Each of them has a dictionary.＝
Every one of them has a dictionary．
（1）each可指两者或两者以上,every至少指三者
(2) each 可做主语,宾语,表语,同位语和定语,every指可做定语
（3）都可与单数名词搭配,但every后可接“基数词+复数名词”,表示“每.”
如：every three days（每3天）
（4）都可做“每一个”解释,但every“总和”意义很重,each“个别”意义较重