True north changes with time, whereas magnetic north, keeps the same at a fixed point. Also, true north is some fixed point on the globe, and magnetic north is the direction the compass needle points out. Let us check the definition and what is the true north below.
True north definition
True north also called geographic north is the direction of the line of longitude that intersect the quadrangle. All the longitude lines converge to points at the north and south poles.
In other words, true north, as opposed to magnetic north, is determined by drawing an imaginary line through the Earth.