What is the difference between "emoji" and "emoticon"?

How did the letter Z come to be associated with sleeping/snoring? ufay2k

• Often I find people in the chat using emoticons. Most are simple to decipher, but I can't figure out what these two mean. :3 and :S What do they mean?
• The emoji sets used by Japanese cell phone carriers contain a large number of characters for emoticon , along with many other non-emoticon emoji. Are emoji the same thing as emoticons? Do take …

Is a smiley at the end of a sentence like a period? ufay2k