A Phrase is a group of words that dose not make complete senses, dose not contain a finite verb, expressed or understood , but is used as single part of speech.
Examples: Come at once. He come to see me. She was at the point of death.
A Clause is a group of words having a subject and a predicate of its own, but forming part of a sentence.
Examples: I know that he is ill. The boy whom you saw is my brother.