The word icon has several different meanings, but here it is used to describe a symbol or graphic representation on a computer screen. So, when someone says hover your mouse over the Windows icon, you know you are looking for this symbol .
The word emoticon is a mix of 2 words - emotion, and icon. An emoticon is also a symbol, but it is used in text messages or emails to show how someone is feeling. It is made up of symbols found on your keyboard. For example the ubiquitous smiley :), but emoticons can express more complex emotions - this is the "shrug" emoticon - ¯\_(ツ)_/¯ It is known as a shruggie, and symbolises the body language of raising both shoulders to show your indifference about something or that you do not know then answer to a question. It is made up of 11 keystrokes.
Emoji are also used in electronic communications such as an email or text messages to express an emotion or idea, but emoji are images, for example the wink emoji - 😉.
Watch the presentation below to learn more about emoji and emoticons.