Every wave has its own velociry and two or more than two waves create a wave packet like wise when many people get together ,they form a procession where each indivisual person in procession ,has its own speed and procession moves with a common speed ,called resultant speed or resultant velocity.The velocity of a component wave of a wave packet is called phase velocity and the velocity of a complete wave packet is called group velocity. You can better understand this with the help of some videoes which are attached here.
