Question

Every set is a collection of object but every collection of object is not a set examples

Answer 1

A set is defined as the well defined collection of objects.
eg: {2,3,5}

But there are collection of objects which are not set. We cannot have a set containing everything (real numbers, complex numbers, chickens, spoons,etc.) and that some collections of objects are simply not sets.
So every collection of objects is not set