what is the difference of the folder t_reconstruction_system and reconstruction_system ?

[citystrawman]

Checklist

• [X] I have searched for similar issues.
• [X] For Python issues, I have tested with the latest development wheel.
• [X] I have checked the release documentation and the latest documentation (for main branch).

My Question

Hi, I am learning the reconstruction system and in the official tutorial Quick start , the code asks me to direct to folder reconstruction_system and then execute the dense_slam_gui.py: cd examples/python/reconstruction_system/ python dense_slam_gui.py --help

But from the latest main branch I could only find dense_slam_gui.py in folder t_reconstruction_system.

Then the following tutorial asks me to execute run_system.py which exists in both t_reconstruction_system folder as well as reconstruction_system folder.

My question is, what is the difference of the folder t_reconstruction_system and reconstruction_system ? and can I just use the run_system.py in t_reconstruction_system folder?