How do I find correlation between two GNSS routes?

As seen in the image i have a GPS route from a ublox GPS and a GPS route from an Novatel RTK GPS. I also have the loosely coupled INS solution plotted together with the two GNSS solutions.

It can be seen that the RTK GPS (purple) route together with the loosely coupled INS(RTK) solution (green) is somewhat displaced/shifted down and to the left compared to the ublox GPS (blue) and the loosely coupled INS(ublox) solution (red). The yellow is the RTK GPS position calculated using baselines, this is also shifted a little but not as much.

I am looking for a function which can find this shift (correlation?) so that all the GPS routes becomes somewhat aligned, or at least start in the same position. I have been looking at the function xcorr2 but i dont understand the result and how it will help me align the GPS routes.

The data is gathered from an UAV flying with both GPS's and an MTi10 IMU so the data should theoretically be on top of each other.

EDIT: the data is in the following format:

INS_RTK_utm_coords = [East North height]

So i have tried using the xcorr2 function:

xcorr2(INS_RTK_utm_coords, INS_ublox_utm_coords)

This gives me a matrix with 5 columns and double the length of the INS_RTK_utm_coords which i guess is correlation values at the different lag. But how i go from correlations to moving my GNSS routes so they are atop each other is grey for me.

EDIT: I want it to look something like this:

Here i simply added 2.7 meters to all east coordinates and 2.3 meters to all North coordinates, however these numbers are just from my eyesight looking at the top plot. I want to calculate the best "numbers" so that they are aligned the most.