Pull ups are a challenge to many people and impossible for some. Pull ups build upper body strength quickly by increasing arms, back, abdominal strength and tone muscles. They also strengthen your fingers and hands.
The best way to start with pull ups is to start with pull downs. They help prepare and train your upper body for the pull ups. On the pull downs, gradually increase the weight used.
You can start your pull ups by assisting yourself with a chair with one foot on the chair, band, or an assisted machine to build your upper body strength. Gradually push yourself for that extra rep but be careful not to push too hard and strain a muscle (from experience).
The difference between a pull up and a chin up is your hand positioning. The pull up is done with an overhand grip and the chin up is done with the palms facing towards you. You can even place one hand in a pull up position and opposite hand in a chin up position for variation.
I hope you grow to enjoy the pull ups they are a great exercise and make them a part of your exercise routine.