Coordinates or Grid References?
Some may prefer the more precise definition that coordinates are where the main vertical and horizontal lines on a map intersect (therefore an exact location) and grid references are in between these lines (and therefore not as exact location). A grid reference is only a coordinate where the main lines meet. This ‘logic’ falls apart when one considers that the coordinates referenced may be part of a larger graticule and therefore they may be inside other coordinate lines.
How to describe a Coordinate/Grid Reference
There are numerous coordinate systems:
Degrees Minutes Seconds (DMS)
Universal Transverse Mercator (UTM)
Military Grid Reference System (MGRS)