A class module as a whole contains the “blueprint” for an instantiatable object.
A module is a container for code. The Public elements of a module are available to the entire project, with no further setup required. If you modify the value of a Public variable in a module, all code that reads it will see that value.
In the case of instantiations of a class (the instantiations are called objects), the instances of variables declared as Public are unique—change one and no others are thereby changed.