A laughing man is sitting in a camp chair with his arms outstretched, while a man in a black shirt next to him is stuffing his face.
the man was laughing at the man who was stuffing his face
The laughing man may have been laughing about something entirely unrelated to the man stuffing his face.  He may have been laughing at him, but he may have been laughing with him.
A laughing man is sitting in a camp chair, while a man next to him is stuffing his face don't necessarily imply the man was laughing at the man who was stuffing his face.
You can not infer the man was laughing.