Difference of ros2 demos and ros2 examples

Next Generation ROS
1

as the question has been unanswered on answers.ros.org I hope here someone kindly comments

Tutorials refer to ros2 demos and to ros2 examples and both are actively maintained
both seem to rely on example_interfaces in /opt/ros/crystal/share/example_interfaces

Is that a historically grown thing ? if not when should I to look at which ?
Or in other words how would I extract the right files/infos to compose my own ros2 project ?

2

As the support guidelines state, please do not ask your question more than once. Your question is up and visible at answers.ros.org. If no one has answered yet, it’s because no one who knows the answer has seen it yet or had time to answer. Probably because you asked your question at the weekend.