With Snapchat there is no social pressure involved in the form of likes or comments. This makes teens more comfortable sharing their own pictures without having to worry about anything. See why do people like Snapchat.
Because Snapchat pictures disappear, teens are not pressured to perfect their pictures, and as a result, they feel more free using Snapchat than Instagram or Facebook. Teens are usually overly concerned with their physical looks and this gives Snapchat a strong advantage over other social networks.
Many teens don't like Facebook and describe it as the social network for grownups. Many teens prefer Snapchat over Facebook to move away from their parents and relatives. See Why teens don't like Facebook.
Many teens use Snapchat to privately message their close friends or the ones they trust. Other social networks are more open and are not that private compared to Snapchat. This gives teens more freedom to post and makes them feel more comfortable. See how Snapchat started.
Many teens prefer Snapchat over WhatsApp at certain times because of its visual nature. Snapchat is considered more interesting to teens since it allows them to share pictures in an easier way. See why Whatsapp is so popular.
Teens like to have fun and Snapchat helps them do so well. With its funny filters, Snapchat turned the messaging process into a funny way of communicating with others. See why Snapchat filters sometimes don't work.
Snapchat gives people the ability to know who viewed their pictures. Teens can get a self-esteem boost when they know that a certain person wanted to view their picture.
Teens are always interested in being cool. Snapchat is considered the latest cool thing and this motivates many teens to use it. See why Facebook offered to buy Snapchat.
Teens usually have a low attention span. The fact that Snapchat is very fast to use has made it more popular among them. See why your attention span is getting lower.
Teens are usually more focused on the present than adults. Teens thus love to share moments with their friends as they enjoy them and Snapchat allows them to do so easily. See why Snapchat might be bad for you.
Filters make teens, who are already obsessed with their looks, look better. The funny filters were designed to enhance people's looks and that's why they are very appealing to teens. See why Dog Face filter pictures are so popular.
The fact that Snapchat doesn't show the friend list count removes an additional pressure that other social networks such as Instagram and Facebook have.
Since Snapchat is popular among teens, many of them use it to differentiate themselves from adults and older people who use other social networks.