Hi @mattsmith2, apologies for the delay in reply.. both the Tobii Pro SDK and XR SDK belong to different business so getting a comparison took longer than expected.
So, the principal difference between the two SDK’s is the XR SDK is aimed at usage within Interaction Applications only whilst the Pro SDK permits usage for analysis and research use. Any intention to use the XR SDK for analysis requires the purchase of a special licence to do so.
In addition, the Pro SDK can create and handle custom calibration routines, the XR SDK relies on the Tobii Core Software integrated Calibration Program to operate.
Otherwise, the differences are slight so it really depends on your project intentions.
Please let us know if we can be of any further assistance.