A man in a white shirt speaks into a microphone as other men gather behind him at a public event.
The man speaking is the President of the United States.
The President of the United States may or may not wear a white shirt and any other man could be wearing a white shirt.
A man in a white shirt speaks into a microphone as other men gather behind him at a public event doesn't imply he is the President of the United States.
Every man speaking at a public event is not necessarily the President of the United States.