While emoticon is a textual expression representing the face of a writer's mood or facial expression.
Smiley has been a registered trademark in some countries since 1971 when French journalist Franklin Loufrani created "Smiley World" to sell, advertise and license the smiley face image in the United Kingdom and Europe.
The first person documented to have used the emoticons :-) and :-(, with a specific suggestion that they be used to express emotion, was Scott Fahlman; the text of his original proposal, posted to the Carnegie Mellon University computer science general board on 19 September 1982 (11:44), was thought to have been lost, but was recovered twenty years later by Jeff Baird from old backup tapes.
source : Wikipedia
There are few styles of emoticons; Western style, Asian style, Korean style, Western use of East Asian style, Mixture of western and East Asian style, and more.
For more info, click HERE (Emoticons) or HERE (Smiley) .