Phrase, as mentioned previously is the combination of words giving no meaning. Remember, only full composition unit is meaningful, not a half one. In this sense Sentence is the full unit and Clause and Phrase is the half. Even one word is not giving complete meaning, e.g. horse is one word and doesn’t give complete meaning. If I just say horse what can anyone understand from just the word horse until it is meaningfully combined together.
Sentence is defined as completely meaningful combination of words from one full stop to another full stop except first sentence. Sentence starts with the capital letter. Sentence may be of one clause (simple), main and subordinate clause (complex), two independent clauses (compound) and more than two clauses (complex-compound). Simple sentence is also called clause.