different calculation results

I spend a comparison of functions of spatial analysis and Oraсle postgresql. There are two tables with the same coordinate system – tech_bridge.

oracle query

select sum(SDO_GEOM.SDO_AREA(t.gdo_geometry,1)) from geo.tech_bridge t

result : 167615.3831

postgresql query

select sum(ST_Area(t.gdo_geometry, true)) from geo.tech_bridge t

result : 167508.4431

why the results are different?