This is a very important point to make. It's even possible for an introvert to be more outgoing and sociable than an extrovert. The E/I axis is very narrowly defined in MBTI (I guess you might not be using it in that sense since this is in General Psychology, though clarification would be important in that case), such that many of the common beliefs concerning introversion and extroversion don't necessarily apply.What defines an extrovert is someone who gains energy from being around people while introverts on the other hand use energy by interacting with others. Naturally, an introvert would usually be more quiet and reserved while an extrovert would be outgoing and sociable. However there are instances in where an introvert at times can be a chatterbox. For example, if you were to talk to an introvert one on one about a topic they like, they'll continue talking about it on and on. Extroverts can also be certainly silent at times, usually when in a moody state. So under certain conditions, an introvert can certainly seem more outgoing than an extrovert and an extrovert can seem more shy than an introvert. This also depends on the person themselves and any conditions they have, an extrovert with social anxiety may seem like introvert until you get to know them well,soon enough they'll be around you a lot.