TF2 Object Detection API config

I found that there exist 2 config files for most of the models:

• one lies at https://github.com/tensorflow/models/tree/master/research/object_detection/configs/tf2
• the other is included when you download the pre-trained weights at model zoo https://github.com/tensorflow/models/blob/master/research/object_detection/g3doc/tf2_detection_zoo.md

What are the differences on them?