You can use Ferret for plotting wind vector anomaly from two different data sets.

Set data ERA .nc

Set data GFL.nc

let u_anom=u_variable_name[d=1]-u_variable_name[d=2]

let v_anom=v_variable_name[d=1]-v_variable_name[d=2]

vector u_anom,v_anom

this will show the anomaly wind vector.

You can also easily plot graph of wind vector anomaly using ferret .

You can compute anomaly for u and v wind separately then plot the vector using both the results