Regarding traditional maps, in addition to the specific symbology, there is another characteristic in Orienteering maps that is specific to this sport: the meridians are oriented not towards Geographic North, but towards Magnetic North.
Magnetic north lines
North Lines are parallel lines drawn from Magnetic South to Magnetic North, spaced generally 500 meters (1:15000) or 250 meters (1:10000). These lines are blue or black.
The North Lines on Orienteering maps do not point to Geographic North as on most other maps, due to the fact that compasses (equipment used by most orienteers) indicate Magnetic North and not Geographic North. Thus, Orienteering maps only have magnetic north lines.
Magnetic declination is the angle between the true north line (Geographic North) and the line pointed by the compass (Magnetic North), to the East (positive) or West (negative). This declination varies depending on where you are in the world.
Magnetic declination also varies over time.