Here are the new CMake changes in Qt Creator 16:
More feature parity with QMake projects
In Qt Creator 16, it is about grouping of empty subdirectories.

Objective C/C++ support
Qt Creator 16 properly loads projects that have the OBJC
and OBJCXX
languages explicitly set in CMake.

Runnable configurations from CMake custom targets
Qt Creator creates runnable configurations for executables. But what happens if you have a plugin that you would want to test?
Qt Creator 16 will create a Run configuration for the add_custom_target
targets that have the qtc_runnable
value set for the FOLDER
target property.
Qt Creator uses this feature for the Qt Creator Plugin Wizard.
add_custom_target(RunQtCreator
COMMAND ${QtCreatorExecutable} -pluginpath $<TARGET_FILE_DIR:Testplugin>
DEPENDS Testplugin
)
set_target_properties(RunQtCreator PROPERTIES FOLDER "qtc_runnable")
CMake targets and the associated CMakeLists.txt file node
The change was done in Qt Creator 15 and it was not that well received 😅
Qt Creator 16 partially reverts this change.
Qt Creator 16 only keeps the associated CMakeLists.txt
file node for targets that have the FOLDER property set.
ChangeLog
For all the CMake changes see Changelog # cmake.