The most important thing to remember is that "every" doesn't work if there are only two objects to refer to. For instance, "I have tattoos on each hand" works but you can't say, "I have tattoos on every hand". With more than two objects they are interchangeable - "I have blisters on each toe" OR "I have blisters on every toe".

They can usually be used interchangeably. There are some cases where they can't: "I'm giving you five dollars each." "You spent every single dollar on candy." "I'm giving five dollars to each of you." "I'm giving five dollars to each one of you." "I'm giving five dollars to every one of you." (Basically "each of"/"each one of" and "every one of" can be used interchangeably.) But there are many cases where either one is OK: "I spend each/every day the same way." "Each/every time it rains I get wet." "I want kiss each/every girl I meet." The difference in meaning is subtle, but "each" to me seems more like treating things individually, and "every" to me seems more like treating them as members of a group. But in practice it's hard to clarify more than that.

Sometimes, "each" and "every" are used interchangeably, however, it's normal to use "every" when referring to a group and "each" when referring to single.

That's a tricky one . . . They kind of mean the same thing and are often interchangeable. In addition to Sam's comment, my thougts are: EVERY means the group as a collectiion. EACH means every individual member of the group. That's my opinion, at least.