Based upon the definitions, shouting would be more sudden and shorter in duration whereas yelling more elongated. "The father shouted when the kids scared him." "The drunk people were yelling while they walked down the street."

'Yelling' suggests a sound which is more out of control. 'Yelling' also suggests that the speaker is irritated by or disapproving of the sound being made. For example, in the sentences which Max gives, the speaker probably things that the 'shouting' is justified, but was annoyed or disturbed by the drunk people who were 'yelling.' 'Yell' is used more in US English than in other varieties of English, particularly when used in the sense of a parent being angry with a child.