Dreams are characterized by bizarreness. Time, place, and characters change seemingly at random, but during the dream seem perfectly normal. Places, people, and things act in ways completely out of context. That is, 'the building seems to have grown' as opposed to 'the building grew'. Dream events often do not occur in logical sequence.
Visual content is often the key source of information, along with audition and movement.
Dreams do not often come with a sense of smell.