Greetings from Balochistan!

I have ground control points ( including elevation data) data taken with total station. When I entered adjusted coordinates in RC of Matrice 300, saving data failed due variation of about 21 metter in elloposoidal height. I checked ellevation with use of two different handheld GPSs: both the GPSs showed almost same elevation  but the difference between elloposoidal height of D-RTk-mobile station and elevation of GPSs was more than 20 m. Since I'm not a surveyor, I can't figure out the issue. Any guidance please? Are elliposoidal height and ellevation shown in GPSs same  type or some sort of conversion required?

Greetings from Balochistan!

I have ground control points ( including elevation data) data taken with total station. When I entered adjusted coordinates in RC of Matrice 300, saving data failed due variation of about 21 metter in elloposoidal height. I checked ellevation with use of two different handheld GPSs: both the GPSs showed almost same elevation  but the difference between elloposoidal height of D-RTk-mobile station and elevation of GPSs was more than 20 m. Since I'm not a surveyor, I can't figure out the issue. Any guidance please? Are elliposoidal height and ellevation shown in GPSs same  type or some sort of conversion required?