Each is a pronoun, as well as an adverb; however, everyone is only used as a determiner with a countable noun such as: “each day gets better and better.” The word each in the sentence demonstrates more than one. The word each separates.
The main difference between the words each and every is that everyone puts people or things into a group, while each implies separation, but the person or place remains the same. For example, “Every time I believe him, he disappoints me greatly.” Its usage is something like that of the word all. Each, on the other hand, is a determiner with a countable noun.