What are the differents between turtlebot2_kobuki and turtlebot_burger above on Odometry topic?

Hello, I'm using ROS kinetic with Ubuntu 16.04.

It is clear that turtlebot2 is different from turtlebot3, but when I launch turtlebot2 with gazebo simulation and give it velocity topic, and also it collides with the wall, and still give velocity topic continuously, the position of its/odom increases infinitely at the crushed position.

In the case of turtlebot3_burger, the /odom does not increase anymore.

Anyone who knows this reason?

If so, would you happen to please give me the proper explanation?