Contour line error

Hi, I would like to know why contour line generated from Pix4 is different from  Google elevation.The elevation generated from pix4 pro is different from google earth elevation around 3 to 5 meters. I put contour base 0.00 and interval 0.5 and i tried to use different contour base but the result were wrong compared to Google earth elevation? so does anyone have any idea about this? Now I just updated Pix4D pro but it still get the contourline incorrect compared to Google earth elevation. Thank you for any idea. 

Google Earth elevations come from a different data source, they will be different elevation because of this.

Dear Chenda, Mark,

Mark is correct: this is not the same data source, and an inaccuracy of 3 meters is to be expected for Google elevation data.

Best regards,