The document discusses the difference between a clause and a phrase in English grammar. A clause is a group of words that contains both a subject and a verb, while a phrase does not contain both a subject and a verb. Examples of clauses include "He laughed" and "She is cooking", while examples of phrases are "On the table" and "Under the tree". Both clauses and phrases can exist within a sentence, such as in the sentence "He is sleeping on the bed", where "He is sleeping" is a clause and "on the bed" is a phrase.