When you are exporting your results from RealityCapture you have more options there with regards to the selection of the coordinate system. There could be two cases. The first case is a non-georeferenced environment, the second case is georeferenced.
When you have a non-georeferenced project you can export in "Grid" or "Same as XMP" coordinate system.
When you have a georeferenced project there are added two options: Output coordinate system and Shifted output coordinate system.
Grid plane coordinate system is related to the grid which is visible in the 3Ds view. It can be considered a local coordinate system. The axis are oriented (when you are looking from above): Y is pointing to the north and it is the green arrow, X is pointing to the east, it is the blue arrow and Z is pointing up as the red arrow.
The grid coordinate system is related to an actual 3Ds view and model's position, so if you use the Set ground plane tool after model computation, there will be different grid plane model coordinates as before this change.
In this image, you can see the model placed in the grid's zero position. This means that the model's coordinates will be around 0 for the X and Y axis.
Same as XMP
The XMP coordinate system is related to the XMP data and could be different from the grid coordinate system. This is the system and coordinates that you get after the first images' alignment.
In this image, you can see the previous model in the "Same as XMP" coordinate system. The model is not in the zero Z grid position but it is slightly above it:
A good explanation of the difference between these exports' coordinates systems is visible when we compare two exported models in one application in their basic positions.
In this image, the upper model is exported in the "Same as XMP" coordinate system and the lower model is exported in the "Grid plane" coordinate system.
This option is only available when your project is georeferenced (in local or global coordinates). The project output coordinate system is one that is set in the application settings. To set the output coordinate system go to the Workflow tab/Application/Settings/Coordinate systems. You can use a local Euclidian coordinate system, one of the predefined global coordinate systems, or one of your own coordinate systems (https://support.capturingreality.com/hc/en-us/articles/4771191909148-Set-your-own-global-or-local-coordinate-system).
Shifted project output
This coordinate system has the same orientation as the project output coordinate system but it is moved to the center of the reconstruction. Basically, the zero of this coordinate system is located in the zero of the grid and it is in the center of the firstly aligned component.