Phrases are a group of words that sort of work together eg" the hairy spider". Phrases do not have a subject AND a verb eg "running fast" is a phrase containing a verb (running) but "the boy was running fast" is not a phrase because it has a subject, the boy, and a verb (running).
Now clauses contain a subject AND a verb l. "The boy was running fast" is a clause and so is "I said", I bring the subject and said being the verb.
Hope this helps :)