The strength and direction of the actual wind blowing. While sailing, the true wind is never felt - it is always a combination of the true wind, and the boat's speed (called the apparent wind), and it is always a little forward to the true wind.
Direction and velocity of wind as measured on land, distinct from apparent wind.
The actual speed and direction of the wind felt when standing still.
the speed and direction of the wind. The motion of a boat will cause the wind to appear to be coming at a different direction and speed, which is known as apparent wind.