Note that displacement is a vector quantity - it has magnitude and direction.
Distance is a scalar quantity - magnitude only.
So from you question (should use distance = initial velocity x time +1/2 accelerationxtime squared, but no accel, so just becomes velocity x time)
Distance = 8 x 15 = 120 metres
Displacement would be, for example, 120m North or 120 metres at a bearing of 0 degrees etc.