What term describes the angular difference between true north and magnetic north?

The term that describes the angular difference between true north and magnetic north is variation. Variation, also known as magnetic declination, is the angle that shows how much the magnetic north differs from true north at a specific location on the Earth's surface.

Understanding variation is crucial for navigation, as it enables pilots and navigators to accurately adjust their headings based on the differences in north orientation while using magnetic compasses. Due to variations in the Earth's magnetic field, this angle can change depending on geographic location, making it important for accurate navigational calculations.

In contrast, deviation refers to the error introduced in a magnetic compass reading due to nearby magnetic fields from electronic devices or metal structures. Heading denotes the direction in which the aircraft's nose is pointing, while drift typically refers to the lateral movement of an aircraft due to winds or currents rather than any angular relationship with north. Each of these terms has its distinct context and meaning in aviation, but variation is specifically associated with the difference between true north and magnetic north.