Azimuth angle results are different for 'Field Calculator' and 'Measure Angle' on QGIS

After changing coordinate reference systems of line layer and project to TM 36N ED50 (projected coordinate system), I recalculated it again. Now azimuth angle and measured angle are the same. I used WGS84 geographic global coordinate system before. Because of the north of global coordinate system is different from metric local coordinate system, there was 7° difference between measured angle and calculated azimuth.