The example in this article shows how to reduce the differences between the output of the Projector sample extension and the ArcInfo PROJECT command.
This is related to mismatches in either spheroid, datum, or both. When projecting in ArcInfo, the default spheroid for UTM and the two Stateplane coordinate systems is Clarke 1866, whereas in ArcView it is GRS80 for UTM, and Stateplane NAD83 and Clarke 1866 for Stateplane NAD27.
For example, for a coverage with the following parameters:
Stateplane California Zone VI (3401) NAD83
Starting with the same Stateplane coverage in ArcView, use the following parameters for projecting it into UTM:
Category - Stateplane NAD83
Type - Calif. Zone VI
Category - UTM
Type - Zone 11
Even if the output spheroid is set to Clarke 1866, the results will not match ArcInfo. The Projector extension does not support datum transformations. It is necessary to use the Datum Conversion extension or the NADCON extension available from ArcScripts.