There are lots of differences  between these two.
I was confused at first just like someone confused on her sex status whether she is straight,gay or bisexual... I wanted to be outgoing but I later came to the realization that I'm reserved.

However, being an introvert doesn't make you shy; don't get it wrong. I'm not saying that some introverts aren't shy but not all cos there is a slight difference though they seem alike.
An introvert minds his/her affair and rarely talks just like a shy person but that doesn't mean they are easily frightened or fearful.
They can be confident but just like to keep to them selves not wanting to interfere in people's lives and doesn't want people to interfere with their affairs.   ...