Would it right to say that geodetic coordinates (phi & lambda) are the same as latitude & longitude?
This is a great question because it uncovers important sources of common misunderstandings. The brief answer is that although of course geodetic latitude and longitude are a form of latitude and longitude, they are not the only ones and the differences are not trivial, so we should be cautious not to confuse them.
In all cases, latitude and longitude are numbers used to designate points on the earth's surface. Usually, the definition of longitude is straightforward because all but the most detailed models of the earth's surface assume it is rotationally symmetric. (Geoids, which account for gravitational anomalies, are a possible exception, but this level of detail is normally used only to develop precise elevation coordinates without modifying the underlying latitude and longitude.) Lines of longitude are meridians and can be designated by the angle they make with a designated meridian of origin, a "prime meridian."
There are many different kinds of latitude. They are best discussed in a context where an ellipsoidal model of the earth is given, such as the WGS84 or GR80 ellipsoids. The latitude depends on the reference ellipsoid. (This is important when using data referenced to historical ellipsoids, such as the Clarke 1866 ellipsoid. With more recent ellipsoids, established through satellite measurements, the differences are so small as to be of interest only when accuracy and precision needs are extremely high (sub meter).)
When we change the model of the earth (the reference ellipsoid), we obtain a different set of latitudes altogether. Frequently this happens when a latitude based on an ellipsoid is considered to be a latitude based on a spherical model. I recently analyzed the resulting error at Approximating earth as sphere, finding the displacements (between the correct location designated by a latitude and the apparent location) can be as great as 20 km. Differences among the various latitudes in use (see "additional latitudes" above) can be of the same order of magnitude, so even for very rough mapping purposes one should pay attention to what is going on.
A good, but highly technical, source of information on many forms of latitude is
Bugayevskiy, Lev M. & John P. Snyder, Map Projections, A Reference Manual. Taylor & Francis, London (1995).
See pp. 33-37 for formulae and Appendix 5 for a table of isometric latitudes.
Yes, to quote Wikipedia:
But, as Alex Markov commented, to keep in mind datums
I think this would be an adequate explanation for you (pls read all of them.)...
i hope it helps you...