We have learnt that sentences consist of words put together in a structured manner to help communicate thoughts. The sentence is normally divided into a subject and a predicate. Obviously, this means that both the subject and predicate comprise words drawn from different parts of speech. These words are strung together based on the rules of grammar so that everyone who is aware of the rules is able to follow.
By themselves the groups of words representing subject and predicate are known as a phrase. Thus, phrases are groups of words that fall short of being called sentences because they communicate thoughts partially. While the sentence has a subject and a predicate the phrase has only one of them.
Typically, there are noun phrases and verb phrases representing subject and predicate respectively. For instance: