Hello GIS Grinder, today going to write on differences between WGS84 and NAD83. Both the coordinate system differ in some way, I have listed 10 differences. This minor differences are important for any GIS expert to know.
1. WGS84 (World Geodetic System of 1984) uses WGS84 ellipsoid where as NAD83 (North American 1983 Datum) uses the Geodetic Reference System (GRS80) ellipsoid.
2. WGS84 has 0.21mm longer ellipsoid than NAD83.
3. WGS84 is used all over the world where as NAD83 is mostly used in USA and Canada.
4. WGS84 has error less than 2cm from center of mass which is better than NAD83.
5. One other main difference between WGS84 and NAD83 is points over Northern American plate for NAD83 does not change whereas WGS84 is defined with respect to average of stations all over the world.
6. Revised WGS84 has deviation of 105 m to +85 by the use of new EGM96 geoid which differs from the original WGS84. NAD83 has not changed.
7. NAD83 has 250,000 points all over the USA and Canada that includes 600 satellite Doppler stations. WGS84 does not have any physical coordinates.
8. WGS84 is used by the U.S. Department of Defense where as NAD83 by number of government agencies.
9. Different Parameters for WGS84 vs NAD83
| Coordinate system Name | Ellipsoid | Semi-Major Axis | Semi-Minor Axis | Inverse of flattening |
| WGS84 | WGS84 | 6378137 | 6356752.3142451793 | 298.25722356300003 |
| NAD83 | GRS80 | 6378137 | 6356752.3141403561 | 298.25722210100002 |
| Difference in Value | 0 | 0.00010482 | 0.000001462 |
Note: There is a small difference in parameters for Semi-Minor Axis and Inverse of flattening which might be negligible during survey.
10. WGS84 vs NAD83 North America Map
Md. Monzurul Haque.
26 Dec 2019Thanks for your DEscription.