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This terminology is generally sourced from Appendix A of 'Datums and Map Projections' (Iliffe & Lott 2008) based off the ISO 19111 terms.
Term  Comment 

Coordinate  A sequence of n numbers designating the position of a point in ndimensional space 
Coordinate conversion  Change of coordinates from one CRS to another in which the two CRSs are based on the same datum 
Coordinate operation  Change of coordinates with a 1to1 relationship, from one CRS to another. Comprised of coordinate conversion and coordinate transformation processes 
Coordinate reference system (CRS)  A coordinate system that through a datum, has defined position, scale and orientation with respect to an object (usually the Earth) 
Coordinate system  Set of rules defining how coordinates are assigned to points 
Coordinate transformation  Change of coordinates from one CRS to another, where the CRSs datums differ 
Datum  Defines the position of the origin, the scale and the orientation of the axis of a coordinate system with respect to an object 
Easting  Distance in a CRS eastwards from a northsouth reference line, positive eastwards 
Ellipsoid  A closed surface formed by the rotation of an ellipse about a main axis. The figure of the Earth is usually modelled as an ellipsoid which is slightly squished from the shape of a sphere at the poles. Shape usually described by terms a and b (semimajor and semiminor axis lengths) or a and finverse (inverse flattening) 
Ellipsoidal height (h)  Distance of a point from the ellipsoid, measured along the perpendicular from the ellipsoid to the point 
Geodetic CRS  A CRS where position is specified by geodetic latitude, geodetic longitude and (for 3d case) ellipsoidal height 
Geodetic latitude  Angle from the equatorial plane to the perpendicular to the ellipsoid through a given point, positive northwards 
Geodetic longitude  Angle from the prime meridian plane to the meridian plane of a given point, positive eastwards 
Geoid  Equipotential surface of the Earth's gravity field, which is everywhere perpendicular to the direction of gravity and which best fits mean sea level 
Geoidellipsoid separation (N)  Height of the geoid above the ellipsoid 
Gravityrelated height (H)  Height dependent on the Earth's gravity field, such as orthometric or normal height, which both are approximations of the distance of a point above mean sea level. H = h + N 
Height  Either ellipsoidal or gravityrelated height 
Map projection  Coordinate conversion from an ellipsoidal coordinate system to a plane 
Mean sea level (MSL)  Averal level of the surface of the sea over all stages of tide and seasonal variations. Usually defined for a local region from observations of one or more points over a period of time 
Meridian  Intersection of an ellipsoid by a plane containing the shortest axis of the ellipsoid 
Northing  Distance in a CRS from an eastwest reference line, positive northwards 
Prime meridian  Meridian from which the longitudes of other meridians are quantified 
Projected CRS  A CRS derived from a 2D geodetic CRS by applying a map projection 
Vertical CRS  A 1D CRS based on a vertical datum 
Vertical datum  A datum describing the relation of gravityrelated heights or depths to the Earth, usually related to MSL. Ellipsoidal heights are instead treated as being related to a 3D ellipsoidal CRS 