Two men in hard hats and safety neon vests on scaffolding working outside in the daylight.
A school class visits the museum of modern art.
Men in hard hats are not a school class and working outside can not be done in a museum.
The first sentence is about grown up, hard working men with hats and safety vests. The second is about a school class
It is not a school class at the museum of modern art because it is two men outside in the daylight.