We use each and every + singular noun to talk about all people or things. There is no real difference in a lot of cases but sometimes we can just use one.
When to use every:
When to use each:
To refer to individual things or people within a group: I gave one piece of cake to each person.
When there are only two things or people: I fell off my bike this morning. Now I have a scratch on each hand (= on both hands).
With of + the/possessive + plural noun: He invited each of his friends to the party.
It can be used on its own: Do you want cake or ice-cream? - I’ll have a bit of each.