If the puffin is walking rapidly with its head lowered it is saying, "I am just passing through and don’t mean any trouble." This is called a low profile walk and is useful because the colony is very crowded and a puffin is often crossing another puffin’s territory as it walks. The puffins that are guarding burrows usually assume a pelican walk position that has the puffin stand stiffly erect with its beak next to its body and using slow exaggerated foot movements. This makes the puffin look like a soldier on guard duty, which is just what it is doing by guarding the burrow.
I love these birds!