In case Egon hasn't sufficiently confused you... let me take a hack at it.

Can dead men vote twice?

Can - - - - -(C) Compass
Dead - - - - (D) Deviation
Men - - - - -(M) Magnetic
Vote - - - - (V) Variation
Twice - - - -(T) True

There is true north which varies little and can be assumed constant for your purposes. The compass does not give true north. The compass, strictly speaking, does not give magnetic north either.

The mathematical difference between true north and magnetic north is called Variation and variation can and often does vary from location to location. At any given location variation is typically sufficiently constant to be assumed so.

There is also a difference between magnetic headings and compass readings which is called deviation. Deviation may be negligible with your compass use, especially if little or no ferromagnetic substances or electric currents are close to the compass. Try to read your compass while it is NOT NEAR iron, steel, nickle, electric devices, magnets, etc.

A good hand held GPS will typically get you to within several feet (low double digits) of a specific point. Depending on the features of your GPS it may or may not give you a readout of distance and bearing to a reference point or otherwise be useful for your task.

Surveyors use GPS units with temporarily stationed fixed location auxiliary equipment and can get accuracies to within a fraction of an inch. No commercial off the shelf consumer grade units will get even close to that. The best most GPS can do is to deliver good repeatability, i.e. bring you back really close to the same point once that point has been registered by the unit. Absolute accuracy is less. The ability to take you to a specific spot via lat and lon is less accurate than the ability to return you to a spot.

An engineer's compass (style of instrument) is the minimum instrument to use to try to follow metes and bounds. That in concert with a good 300 ft tape should git 'er done if your sight lines are not obscured in heavy brush, timber, or by topography.

Pat