Objects really represent the same thing in all three languages: a bundling of state and operations. What truly differs is their implementation of this idea.
The largest difference is that Python & PHP are class-based object-oriented systems, meaning that the "templates" for objects are pre-defined. When a new intance of one of these templates or classes is initialized, the class's pattern or definition is used to shape the newly initialized object.
See the following links for more information: