Hi Rodrigue,
Phrases are groups of words that act as a part of speech but cannot stand alone as a sentence. The words in a phrase act together so that the phrase itself functions as a single part of speech. So phrases can function as nouns, verbs, adjectives, or adverbs.
A sentence expresses a complete thought and contains a subject (a noun or pronoun) and a predicate (a verb or verb phrase).
I hope you find this helpful.