Answer:
An accident is basically something which is unexpected and done unconsciously without any deliberate effort from the victims side. However risky behaviour is one where the event occurs due to some conscious act on behalf of the involved person. Risky behaviour involves some deliberate actions and he/she is more or less aware of the consequences.
For example: A car hitting a any person who suddenly comes in front of the moving car is an accident. But if the driver drinks and drives and hit a person due to his/her own recklessness then it will be called a risky behaviour.