Difference between visual and inertial ground truths

Hi thank you for your generocity and sharing your code.

I am a little new to this filed, so I am seeking guidance.
I have looked to visual and inertial GTs and I see considerable difference between the positions. What is the cause of this discripancy?
Is it the world geodesy systems that make this difference or what?
I have searched the net, but came up with no answers.

Thank you in advance.