Arcgis10.2 arcmap投影结果与arcEngine中的IGeometry.Project的投影结果进行面积计算存在误差

//原本是地理坐标系

geometry.Project(SpatialReferenceLoader.Load(4527));

double area1 = (geometry as IArea).Area;

geometry.SnapToSpatialReference();

double area2 = (geometry as IArea).Area;