Peptides are, for the most part, grouped by the number of amino acids contained inside them. For example, the briefest peptide, one made out of only two amino acids, is named a “dipeptide.” Likewise, a peptide with three amino acids is alluded to as a “tripeptide.”
Oligopeptides allude to shorter peptides made up of little quantities of amino acids, by and large under ten. On the other hand, polypeptides are made up of more than ten amino acids.
A lot of bigger peps (those made out of more than 40-50 amino acids) are by and large alluded to as proteins.
Even though the number of amino acids is usually an excellent way to tell the difference between peptides and proteins, there are sometimes exceptions.
For instance, several longer peptides have been considered proteins (like amyloid beta). Occasionally, specific smaller proteins are referred to as peptides (for example, insulin).