I have met both types of people.
Let me explain it in detail according to my experience.
Anti social people are those who vent out their anger and feelings of unrest at others whom they think are quite comfortable, well off and blend in the human society. Anti social people are afraid, irritable and in general display hatred towards every being as a whole. They need psychological help otherwise it could lead to them causing widespread harm.
Such behavior can lead to mental distress and they may either end their life or cause harm and even death to others.
Now for my experience.
A few years back, we had to go to town. when we reached a nearby town, we were asked by some people to park our car within an apartment car shed, quickly. My husband did not question and he did so immediately. Soon, we saw a procession of people walking by, holding sticks, long knives and huge stones to throw at any passer by people or vehicles who dared to go against their declaration of no work that day, also known as 'hartal' in India. We were very scared after we saw what they were holding in their hands.
Such people can be termed as anti social people who display mob mania. They destroy anything and everything without any pity.
An introvert is a person whose attitude has been shaped as such from a young age itself. The introvert is basically shy and withdrawn. They can be brought to the forefront through gentle coaxing and warm behavior.
Introverts usually do not mingle easily with others and also do not take initiative in any matter that might require leadership qualities. They cannot express their feelings and emotions very easily and are most insecure.
It could have been influenced by childhood experiences and it will take time to change their attitude and behavior pattern.
Many of my relatives are very shy and it takes time for them to make friends easily. They also are not so successful in life because of this behavior and attitude.