In C++ terminology an object is an instance of a class or struct type. In 3ds Max an object refers to a scene entity. Scene objects are represented in 3ds Max by instances of classes that derive from Object. Scene objects are associated with an INode object that manages an object's geometry, its transform controllers, assigned materials, assigned modifiers, and more using the reference system. Almost all scene objects are parameteric objects, that is their properties are exposed as parameters the user can control.
As a result of the tight association between a scene element and its node, the two are virtually synonymous.