What you describe as a Product Engineer, I call a Senior Engineer/Developer/Programmer/etc.
Your examples essentially differentiate between 1) a person who accomplishes an assigned task because it was assigned to them and 2) a person who knows that there is more to completing a task than meeting the defined requirements.
Your examples essentially differentiate between 1) a person who accomplishes an assigned task because it was assigned to them and 2) a person who knows that there is more to completing a task than meeting the defined requirements.