What is the difference between recombinant and synthetic polypeptides?

Recombinant polypeptides, or proteins, are made using recombinant DNA techniques, while synthetic peptides are made by chemical peptide synthesis. Synthetic peptides have some advantages over recombinant proteins such as the ability to be generated as exact copies of protein fragments. Synthetic peptides are also able use D-amino acids; recombinant polypeptides typically are composed of only L-amino acids, but synthetic peptides can incorporate both forms. This can help in increasing proteolytic activity in some instances. In addition, synthetic peptides can incorporate a larger range of non-proteinogenic amino acids, which is only possible in recombinant proteins through using alternative codons.