Why are proteins divided into peptides and polypeptides?

The peptide is a short polymer. Peptide is another name for protein but is not considered a protein due to its size. A peptide is a compound of two or more amino acids. When an amino acid reacts with another amino group, it will bind to that group, creating a peptide bond. Therefore, when you talk about the main link in the structure of a protein, a peptide bond unites such a structure.
A polypeptide is a compound of amino acids that contains ten or more amino acids. If there are more than fifty amino acids, then they are considered proteins.